On February 10, at a special seminar of the Center for European Nuclear Research (CERN, Geneva), the results of experiments that, without exaggeration, can be called sensational, were presented. A new state of matter has been obtained, in which quarks - "truly elementary particles" (protons and neutrons, in particular, are "collected" from them) - are not bound to each other, but move freely. According to the theory, the Universe was in this state for the first 10 microseconds after the Big Bang. Until now, the evolution of matter could be traced no earlier than to the stage of three minutes after the explosion, when the nuclei of atoms had already formed.
According to the modern theory of the structure of matter, microparticles, called hadrons, consist of quarks - structureless particles less than 10 -16 cm in size, which represent the limit of matter fragmentation (see "Science and Life" No. 8, 1994). Quarks are held together by forces arising from the continuous emission and absorption of gluons by them (from the English glue - "glue"). These forces behave in a paradoxical way: the closer the quarks are, the weaker they are. Inside a proton or neutron, quarks practically do not interact, but when you try to "break" a particle, the strength of their bonds increases millions of times. Therefore, the release of quarks and gluons is possible only by spending colossal energy. It was possible to obtain it in the heavy ion accelerator.
Professor Luciano Maiani, Director General of CERN, believes that the comparison of the results obtained in the framework of the heavy ion acceleration program gave a clear picture of the new state of matter and confirmed the prediction of quark theory. It is equally important that a big step has been taken towards understanding the earliest stages of the evolution of the Universe. For the first time, it was possible to obtain matter in which quarks and gluons are not bound - quark-gluon plasma. This new, fifth, state of matter (solid, liquid, gaseous and plasma, electron-ionic states have been known so far) opens up a vast field for scientific research. Their next stage will begin at colliders (accelerators on colliding beams) of heavy relativistic ions in Brookhaven (USA) and hadrons at CERN.
The heavy ion acceleration experiment was as follows. The lead ion beam was accelerated to an energy of 33 TeV (1 teraelectronvolt \u003d 10 12 eV) in the proton super accelerator (CERN "s Super Proton Synchrotron), after which it hit targets located in seven detectors. Upon collision, the temperature reached a trillion degrees (10 12 K, 100 thousand times greater than inside the Sun), and the energy density is 20 times higher than the density of nuclear matter. Under these conditions, as experimental data indisputably testify, matter passes into a new state, which has much in common with the previously theoretically predicted quark-gluon plasma - "primitive soup", in which quarks and gluons existed separately.
The research program began in 1994 after CERN's accelerators were improved with the participation of a number of institutes in the Czech Republic, France, India, Italy, Germany, Sweden and Switzerland. The new source of lead ions was connected to the previously built proton synchrotron (which carried out the preliminary acceleration of ions) and the proton superaccelerator. Seven time-consuming experiments were carried out to measure various parameters of lead-lead and lead-gold collisions (they were named NA44, NA45, NA49, NA50, NA52, WA97/NA57 and WA98). Some of them were carried out using multi-purpose detectors, which made it possible to register many different particles and obtain global characteristics of events. In other experiments, on the contrary, detectors with signal accumulation registered only rare phenomena. Thus, a general idea of the quark-gluon plasma was obtained from separate "experimental pieces", just as "puzzles" (riddle pictures) or a mosaic are assembled. The data of each individual experiment did not allow us to draw definite conclusions, but together they made it possible to draw up a clear picture of the phenomenon. The technique, based on the comparison of several different results, proved to be very successful.
The implemented project is an excellent example of cooperation and cooperation in the field of physics research. Physicists from more than twenty countries, including Russian nuclear scientists, took part in the experiments.
The results obtained at CERN are an incentive to continue the work. To confirm that the new matter is indeed a quark-gluon plasma, it is necessary to study its properties at higher and lower temperatures. The center for research on the fifth state of matter will now be the Heavy Relativistic Ion Collider at Brookhaven National Laboratory; work will begin this year. It is supposed to investigate the collision of gold nuclei accelerated to an energy 10 times greater than in the Geneva experiment.
A year ago, letters appeared in American newspapers and popular science magazines claiming that the planned experiment was dangerous. Their authors believed that the release of extremely high energy in a very small volume could lead to the formation of a "mini-black hole" that would begin to suck in the surrounding matter. This opinion received such a strong response in the press and on television that American researchers assembled an authoritative expert commission to verify it. The conclusion was unequivocal: such fears are unfounded; the probability of formation of a "hole" is zero.
And since 2005, experiments with heavy ions will also be included in the program of the large hadron accelerator LHC (Large Hadron Collaider) at CERN.
Five experiments were carried out in the laboratory to observe diffraction using various diffraction gratings. Each of the gratings was illuminated by parallel beams of monochromatic light with a certain wavelength. The light in all cases was incident perpendicular to the grating. In two of these experiments, the same number of principal diffraction maxima were observed. First indicate the number of the experiment in which a diffraction grating with a shorter period was used, and then the number of the experiment in which a diffraction grating with a longer period was used.
| Number experiment | Diffraction period | Wavelength incident light |
|---|---|---|
| 1 | 2d | |
| 2 | d | |
| 3 | 2d | |
| 4 | d/2 | |
| 5 | d/2 |
Decision.
The condition of the interference maxima of the diffraction grating has the form: The gratings will give the same number of maxima, provided that these maxima are observed at the same angles From the table, we find that in experiment 2 and 4 the same number of maxima is observed so that number 4, the lattice number 2 has a larger period.
Answer: 42.
Answer: 42
Source: Training work in physics 04/28/2017, variant PHI10503
v B, in which they move along an arc of a circle
radius R v B= 1 T, and the radius R
1) All ions with which experiments are carried out have a negative electric charge.
2) All ions with which experiments are carried out can have different masses.
3) The specific charge (the ratio of the charge of an ion to its mass) of all ions participating in the experiment is the same and equal to C/kg.
4) All ions with which experiments are carried out have the same masses.
5) The charge of all ions participating in the experiment is the same.
Decision.
Different ions participate in the experiment, they can be of different masses and different charges. The specific charge of all ions is the same, can be found using the Lorentz force:
So statements 2 and 3 are true.
Answer: 23.
Answer: 23
Source: Training work in physics 12/21/2016, variant PHI10203
In a mass spectrograph, various ions accelerated previously by an electric field to a speed v, fall into the region of a uniform magnetic field with induction B, in which they move along an arc of a circle with a radius R. The table contains the following data: initial ion velocity v, with which it flies into a magnetic field with induction B= 1 T, and the radius R the circle described by this ion in a magnetic field.
Choose two true statements that can be made based on the data given in the table.
1) All ions with which experiments are carried out have the same electrical charge in absolute value.
2) All ions with which experiments are carried out have the same mass.
3) All ions with which experiments are carried out are positively charged.
4) All ions with which experiments are carried out can be of a different sign.
5) All ions participating in the experiment have the same specific charges (the ratio of the charge of the ion to its mass).
Decision.
Different ions participate in the experiment, they can be of different masses and different charges. The specific charge of all ions is the same:
So statements 4 and 5 are true.
Answer: 45.
Answer: 45|54
Source: Training work in physics 12/21/2016, variant PHI10204
Five experiments were carried out in the laboratory to observe diffraction using various diffraction gratings. Each of the gratings was illuminated by parallel beams of monochromatic light with a certain wavelength. The light in all cases was incident perpendicular to the grating. First indicate the number of the experiment in which the smallest number of main diffraction maxima was observed, and then the number of the experiment in which the largest number of main diffraction maxima was observed.
| Number experiment | Diffraction period | Wavelength incident light |
|---|---|---|
| 1 | 2d | |
| 2 | d | |
| 3 | 2d | |
| 4 | d/2 | |
| 5 | d/2 |
Decision.
The condition of the interference maxima of the diffraction grating has the form: In this case, the more the less diffraction maxima will be visible. Thus, the smallest number of main diffraction maxima was observed in experiment number 5, and the largest - in experiment number 1.
Answer: 51.
Answer: 51
Source: Training work in physics 04/28/2017, variant PHI10504
| A | B |
Decision.
In picture A, we see a permanent magnet and a coil to which an ammeter is connected. With the help of such an experiment, one can observe the phenomenon of electromagnetic induction, which consists in the appearance of a current in a closed circuit when the magnetic flux through the circuit changes as a result of the magnet moving in / out (A - 3).
Picture B shows a permanent magnet and a light magnetic needle. In the magnetic field of a permanent magnet, such an arrow will always be oriented along the lines of force. Thus, with the help of the experiment, the scheme of which is shown in Figure B, it is possible to observe patterns of force lines of a permanent magnet (B - 1).
Answer: 31.
The figures show schemes of physical experiments. Match these experiments with their purpose. For each position of the first column, select the corresponding position of the second and write down the selected numbers in the table under the corresponding letters.
| A | B |
Decision.
In picture A, we see the coil to which the ammeter is connected, and the coil to which the DC source is connected. Current flows through the second coil, it creates a magnetic field around itself. With the help of such an experiment, one can observe the phenomenon of electromagnetic induction, which consists in the appearance of a current in a closed circuit (first coil) when the magnetic flux through the circuit changes as a result of the approach / removal of the second coil (A - 3).
Picture B shows a permanent magnet and a surface on which iron filings are scattered. In the magnetic field of a permanent magnet, the filings are magnetized and oriented along the lines of force of the magnet field. Thus, with the help of the experiment, the scheme of which is shown in Figure B, it is possible to observe patterns of force lines of a permanent magnet (B - 1).
Answer: 31.
p these gases from time to time t. It is known that the initial temperatures of the gases were the same.
Choose two true statements corresponding to the results of these experiments.
1) The amount of substance of the first gas is less than the amount of substance of the second gas.
2) Since, according to the experimental conditions, the gases have the same volumes, and at the moment of time t= 40 min they also have the same pressure, then the temperatures of these gases at this point in time are also the same.
3) At the moment of time t= 40 min the temperature of gas 1 is greater than the temperature of gas 2.
4) During the experiment, the internal energy of both gases increases.
5) During the experiment, both gases do no work.
Decision.
1) According to the Mendeleev-Clapeyron equation Let's consider the initial moment of time. By condition, the volumes and temperatures of gases are the same, and since then
2) In the isochoric process, Charles's law is fulfilled: And, therefore,
3) From paragraph 2 we conclude:
4) The internal energy of one mole of an ideal gas depends only on temperature. When heated, it increases.
5) Since, by condition, both gases are in closed vessels, both gases do not do work during the experiment.
Answer: 45.
Starting to study mechanics, the student assumed that the modulus of sliding friction force F of the bar on the horizontal surface of the table is directly proportional to the modulus of the gravity force of the bar. He decided to test this hypothesis experimentally. Putting a wooden block with various weights on the horizontal surface of the table, the student pulled it evenly, measuring the force F with a dynamometer. The results of measurements of the F values at different values of the gravity of the bar with weights are marked on the coordinate plane (F) taking into account the measurement error. What conclusion follows from the results of the experiment?
1) the conditions of the experiment do not correspond to the tested hypothesis
2) taking into account the measurement error, the experiment confirmed the correctness of the hypothesis
3) the measurement errors are so large that they did not allow us to test the hypothesis
4) the coefficient of sliding friction changed with a change in the mass of the bar with loads
Decision.
The student's hypothesis is that the sliding friction force of a bar on a horizontal surface is proportional to the modulus of gravity acting on the bar. It can be seen from the above results that, taking into account the measurement error, the experiment confirmed the correctness of the hypothesis: all points, taking into account the error, lie on the approximation straight line.
Answer: 2.
The figures show schemes of physical experiments. Match these experiments with their purpose. For each position of the first column, select the corresponding position of the second and write down the selected numbers in the table under the corresponding letters.
| A | B |
Decision.
Figure A shows an installation for observing the pattern of force lines of the electrostatic field of point charges (A - 3).
Figure B shows the scheme of the experiment for observing the potential distribution along a straight conductor with an electric current flowing through it (B - 2).
Answer: 32.
Two different gases, 1 and 2, are heated in two closed vessels of the same volume (1 liter). The figure shows the pressure dependences p these gases from time to time t. It is known that the initial temperatures of the gases were the same. Choose two true statements corresponding to the results of these experiments.
1) The amount of substance of the first and second gases are equal.
2) At the moment of time t= 40 min the temperature of the second gas is twice as high as the temperature of the first.
3) At the moment of time t= 40 min the temperature of the second gas is less than the temperature of the first twice.
4) In the course of the experiment, the internal energy of gases grows.
5) During the experiment, both gases do positive work.
Decision.
According to the Clapeyron-Mendeleev equation, the pressure, volume and absolute temperature of an ideal gas are related by the relation
Find what the ratio of the amount of substance of the first gas to the amount of substance of the second is equal to. In this case, we consider the moment of time in this case by the condition
This means that the amount of substance of the first gas is greater than the second.
The ratio of gas temperatures at
This means that at the moment of time the temperature of gas 1 is less than the temperature of gas 2 twice.
The internal energy of a gas is proportional to its temperature. With an isochoric increase in pressure, the gas temperature increases, therefore, in the course of the experiment, the internal energy of gases increases.
Dissecting cancer, crossing two different flies and creating life in a test tube - all this was done by the guys in the laboratories of Smart Novosibirsk. For the first time - in NSTU.
Fourth but first
“Baba, I already want to study biology!”- a 10-year-old girl in a gray lab coat whines. "Another 15 minutes - and it will begin"- consoles that granddaughter. Meanwhile, more kids come out of the elevator and cautiously approach the registration table.
“Hello, what is your first and last name? How old are you?" - from such words, the guys first freeze, but quickly grow bolder, begin to smile and put on airs. Each young scientist receives a badge of his team: children are divided into five groups, according to age.
Many children come here not for the first time: the Smart Novosibirsk project started back in October. This is a regional partner of Smart Moscow: the Siberian capital became the 17th city where the project came. Children have already mastered three programs, the new one is called "Biological experiments". For the first time it takes place in NSTU.
“Today is the first program on a serious partnership basis - scientific. We really want children not just to do science, but to do it within the walls where they may later learn. So that they understand that Novosibirsk has all the opportunities for development,” says Anna Petukhova, head of the Smart Novosibirsk project.
Another feature of the Novosibirsk project is the active participation of adults. While the children are experimenting, parents are given a popular science lecture and an interactive quiz.
“For adults, our ticket is free - and we just give them the opportunity not to sit on the phone. Parents who bring their children to us, as a rule, are very smart themselves, they love science and everything connected with it. Mothers, and fathers, and grandparents come to us - it's wonderful. In other cities, of course, there are also such moments, but in Novosibirsk this is especially pronounced. Apparently, the academic character of the city is having an effect,” continues Anna Petukhova.
“Will you distribute the living?”
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After 15 minutes, the class hasn't started yet. Acquaintance begins - with laboratories, universities and "teachers". At a small presentation, the children, together with the presenter, guess the names of the laboratories and are divided into teams. The rector of NSTU Anatoly Bataev also comes to greet the guests of the university.
“We have a mercantile interest,” Anatoly Bataev smiles. - Our main task is that in the 11th grade, when you choose the Unified State Examination, you will choose those subjects that our university needs. I hope that you are our future potential students.”
Future students scatter around the classrooms and in one moment turn into real scientists - focused and courageous. Ten-year-old children readily dissect crayfish and joke when the presenter offers to compare the structure of animals with the Madagascar beetle: “Won’t you distribute the living ones?”
The lesson lasts about two hours. Children conduct five experiments: in the laboratories of zoology (crayfish are dissected here), microbiology, genetics, botany and zoology. Each young scientist receives a "laboratory journal" - a kind of waybill where you need to enter the results of research. Some of them will continue beyond the walls of the university: seeds after experiments in botany and flies after genetic experiments will grow at the children's homes.
And the most touching experiment takes place in the laboratory of zoology: observations are made on mice, very harmless ones. "Not a single mouse will be harmed," - this was promised to all participants even before the experiments.
The program for adults at this time is not inferior to the children's program in terms of information content. One of the interactive quiz questions, for example, addressed a popular misconception: Is a plastic bag really more dangerous to nature than a paper one? A tricky problem: if a country has a waste recycling system, then plastic can be used indefinitely, without throwing it away and without polluting the environment. But how environmentally friendly is a paper bag, for which forests are being destroyed?
frugal economy
"Biological experiments" will be held at NSTU twice more, on February 10-11: six programs are planned.
They are designed for children 7-14 years old, the cost of one cycle is 1490 rubles. As Anna Petukhova admits, in Novosibirsk, the high price does not raise questions:
“When people do not see what we are doing, it may seem that it is expensive. But as soon as they arrive, they see that five laboratories with equipment are working at the same time, five full-fledged master classes. And it's not just smoke, ice, tinsel - children do it with their own hands.
After biological experiments, Smart Novosibirsk will present three more programs before the summer: then a break for three months. These are "Surgery", "Science Detective" and "Paleontology". You can buy tickets for all classes.
We are accustomed to consider ourselves reasonable, independent people who are not disposed to inexplicable manifestations of cruelty or indifference. In fact, this is not at all the case - in certain circumstances, homo sapiens surprisingly easily part with their "humanity".
Asch experiment, 1951
The study was aimed at studying conformism in groups. Student volunteers were invited ostensibly to test their eyesight. The subject was in a group with seven actors, whose results were not taken into account when summing up. Young people were shown a card with a vertical line on it. Then they were shown another card, where three lines were already drawn - the participants were asked to determine which of them corresponds in size to the line from the first card. The subject's opinion was asked last.
This procedure was carried out 18 times. In the first two runs, the prompted participants called the correct answers, which was not difficult, since the coincidence of the lines on all the cards was obvious. But then they unanimously began to adhere to a deliberately wrong option. Sometimes one or two actors in the group were told to choose the correct options 12 times. But, despite this, the subjects experienced extreme discomfort from the fact that their opinion did not coincide with the opinion of the majority.
As a result, 75% of the students at least once were not ready to oppose the opinion of the majority - they pointed to a false option, despite the obvious visual inconsistency of the lines. 37% of all answers turned out to be false, and only one subject from the control group of thirty-five people made one mistake. At the same time, if the group members disagreed, or when there were two independent subjects in the group, the probability of making a mistake was reduced by four times.
What does this say about us?
People are highly dependent on the opinion of the group in which they are. Even if it is contrary to common sense or our beliefs, this does not mean that we will be able to resist it. As long as there is even a ghostly threat of judgment from others, it is much easier for us to drown out our inner voice than to defend our position.
The Good Samaritan Experiment, 1973
The parable of the Good Samaritan tells how a traveler gratuitously helped a wounded and robbed man on the road, whom everyone else passed by. Psychologists Daniel Baston and John Darley set out to test how strongly such moral imperatives influence a person's behavior in a stressful situation.
One group of seminary students was told the parable of the Good Samaritan and then asked to read a sermon about what they had heard in another campus building. The second group was instructed to prepare a speech on various job opportunities. At the same time, some of the subjects were asked to especially hurry on the way to the audience. On the way from one building to another, the students met a man lying on the ground in an empty alley who looked as if he needed help.
It turned out that the students preparing the Good Samaritan speech along the way reacted to such an emergency situation in the same way as the second group of subjects - their decision was influenced solely by the time limit. Only 10% of the seminarians, who were asked to come to the classroom as soon as possible, helped a stranger - even if not long before they heard a lecture on the importance of helping a neighbor in a difficult situation.
What does this say about us?
We can renounce religion or any other ethical imperative with surprising ease when it suits us. People tend to justify their indifference with the words “it doesn’t concern me”, “I still can’t help in any way”, or “they can handle it without me”. Most often this happens not during catastrophes or crisis situations, but in the course of everyday life.
Indifferent Witness Experiment, 1968
In 1964, a criminal attack on a woman, which was repeated twice within half an hour, ended in her death on the way to the hospital. More than a dozen people witnessed the crime (in their sensational publication, Time magazine erroneously pointed to 38 people), and yet no one bothered to treat the incident with due attention. Based on these events, John Darley and Beebe Latein decided to conduct their own psychological experiment.
They invited volunteers to participate in the discussion. Hoping that extremely sensitive issues will be discussed, the agreed participants were asked to communicate remotely - using intercoms. During the conversation, one of the interlocutors feigned an epileptic seizure, which could be clearly recognized by the sounds from the speakers. When the conversation took place one on one, 85% of the subjects reacted vividly to what had happened and tried to help the victim. But in a situation where the participant in the experiment believed that 4 more people were participating in the conversation, only 31% had the strength to make an attempt to somehow influence the situation. Everyone else thought that someone else should do it.
What does this say about us?
If you think that a large number of people around ensures your safety, this is not at all the case. The crowd can be indifferent to someone else's misfortune, especially when people from marginal groups get into a difficult situation. As long as there is someone else around, we are happy to shift the responsibility for what is happening to him.
Stanford prison experiment, 1971
The US Navy wanted to better understand the nature of the conflicts in its correctional facilities, so the agency agreed to pay for an experiment by behavioral psychologist Philip Zimbardo. The scientist equipped the basement of Stanford University as a prison and invited male volunteers to try on the roles of guards and prisoners - they were all college students.
Participants had to pass a test for health and mental stability, after which they were divided by lot into two groups of 12 people - overseers and prisoners. The guards wore uniforms from a military store that copied the real uniform of prison guards. They were also given wooden truncheons and mirrored sunglasses to hide their eyes. The prisoners were provided with uncomfortable clothes without underwear and rubber slippers. They were called only by the numbers that were sewn onto the uniform. Also, they could not remove the small chains from their ankles, which were supposed to constantly remind them of their imprisonment. At the beginning of the experiment, the prisoners were allowed to go home. From there, they were allegedly arrested by the state police, who facilitated the experiment. They went through the process of being fingerprinted, photographed and read out their rights. After that, they were stripped naked, examined and assigned numbers.
Unlike the prisoners, the guards worked in shifts, but many of them were happy to work overtime during the experiment. All subjects received $15 per day ($85 adjusted for inflation in 2012). Zimbardo himself acted as the chief manager of the prison. The experiment was to last 4 weeks. The guards were given one single task - to bypass the prison, which they could carry out as they themselves wanted, but without the use of force against the prisoners.
Already on the second day, the prisoners staged a riot, during which they barricaded the entrance to the cell with beds and teased the guards. Those in response used fire extinguishers to calm the unrest. Soon they were forcing their charges to sleep naked on bare concrete, and the opportunity to take a shower became a privilege for the prisoners. Terrible unsanitary conditions began to spread in the prison - prisoners were denied access to the toilet outside the cell, and the buckets they used to alleviate the need were forbidden to clean up as a punishment.
Every third guard showed sadistic inclinations - the prisoners were mocked, some were forced to wash drain barrels with their bare hands. Two of them were so mentally traumatized that they had to be excluded from the experiment. One of the new members, who replaced the retired ones, was so shocked by what he saw that he soon went on a hunger strike. In retaliation, he was placed in a cramped closet - solitary confinement. The other prisoners were given the choice of refusing blankets or leaving the troublemaker alone all night. Only one person agreed to sacrifice his comfort. About 50 observers followed the work of the prison, but only the girl Zimbardo, who came to conduct several interviews with the participants in the experiment, was indignant at what was happening. The Stamford prison was closed six days after people were let in. Many of the guards expressed regret that the experiment ended prematurely.
What does this say about us?
People very quickly accept the social roles imposed on them and are so carried away by their own power that the line of what is permitted in relation to others is rapidly erased from them. The participants in the Stanford experiment were not sadists, they were the most ordinary people. Like, perhaps, many Nazi soldiers or torturers in Abu Ghraib prison. Higher education and good mental health did not prevent the subjects from using violence against those people over whom they had power.
Milgram experiment, 1961
During the Nuremberg trials, many condemned Nazis justified their actions by saying that they were simply following orders from others. Military discipline did not allow them to disobey, even if they did not like the instructions themselves. Interested in these circumstances, Yale psychologist Stanley Milgram decided to test how far people can go in harming others if it is part of their official duties.
Participants in the experiment were recruited for a small fee from volunteers, none of whom caused fear among the experimenters. At the very beginning, the roles of "student" and "teacher" were allegedly played between the subject and a specially trained actor, and the subject always got the second role. After that, the “student” actor was defiantly tied to a chair with electrodes, and the “teacher” was given an introductory current discharge of 45 V and taken to another room. There he was seated behind a generator, where there were 30 switches from 15 to 450 V in 15 V steps. pairs of associations that were read to him in advance. For each mistake, he received punishment in the form of a current discharge. With each new error, the discharge increased. Switch groups have been signed. The final caption read: "Dangerous: hard to bear blow." The last two switches were outside the groups, were graphically isolated and marked with the marker "X X X". The "student" answered with the help of four buttons, his answer was indicated on the light board in front of the teacher. The "Teacher" and his ward were separated by a blank wall.
If the "teacher" hesitated in imposing punishment, the experimenter, whose persistence increased as the doubts increased, urged him to continue using specially prepared phrases. However, in no case could he threaten the “teacher”. Upon reaching 300 volts, distinct blows to the wall were heard from the “student's” room, after which the “student” stopped answering questions. Silence for 10 seconds was interpreted by the experimenter as an incorrect answer, and he asked to increase the power of the blow. At the next discharge of 315 volts, even more persistent blows were repeated, after which the “student” stopped responding to questions. A little later, in another version of the experiment, the rooms were not as strongly soundproofed, and the “student” warned in advance that he had heart problems and twice - at discharges of 150 and 300 volts, complained of feeling unwell. In the latter case, he refused to continue his participation in the experiment and began to cry out loudly from behind the wall when new blows were assigned to him. After 350 V, he stopped showing signs of life, continuing to receive current discharges. The experiment was considered completed when the "teacher" applied the maximum possible punishment three times.
65% of all subjects reached the last switch and did not stop until the experimenter asked them to. Only 12.5% refused to continue immediately after the victim knocked on the wall for the first time - everyone else continued to press the button even after the answers stopped coming from behind the wall. Later, this experiment was repeated many times - in other countries and circumstances, with or without reward, with male and female groups - if the basic basic conditions remained unchanged, at least 60% of the subjects reached the end of the scale - despite their own stress and discomfort.
What does this say about us?
Even when severely depressed, contrary to all the experts' predictions, the vast majority of the subjects were ready to conduct fatal electric shocks through a stranger just because there was a person in a white coat nearby who told them to do it. Most people are surprisingly easy to give in to authority, even if it entails devastating or tragic consequences.
| 21-36
Five experiments were carried out in the laboratory to observe diffraction using various diffraction gratings. Each of the gratings was illuminated by parallel beams of monochromatic light with a certain wavelength. The light in all cases was incident perpendicular to the grating. In two of these experiments, the same number of principal diffraction maxima were observed. First indicate the number of the experiment in which a diffraction grating with a shorter period was used, and then the number of the experiment in which a diffraction grating with a longer period was used.
| Number experiment | Diffraction period | Wavelength incident light |
|---|---|---|
| 1 | 2d | |
| 2 | d | |
| 3 | 2d | |
| 4 | d/2 | |
| 5 | d/2 |
Decision.
The condition of the interference maxima of the diffraction grating has the form: The gratings will give the same number of maxima, provided that these maxima are observed at the same angles From the table, we find that in experiment 2 and 4 the same number of maxima is observed so that number 4, the lattice number 2 has a larger period.
Answer: 42.
Answer: 42
Source: Training work in physics 04/28/2017, variant PHI10503
The optical scheme is a diffraction grating and a screen located close to it parallel to it. A parallel beam of white light visible to the eye normally falls on the grating.
Choose the correct statement, if any.
A. This optical scheme makes it possible to observe a set of iridescent diffraction bands on the screen.
B. In order to obtain an image of diffraction maxima on the screen, it is necessary to install a converging lens in the path of the light beam, in the focal plane of which there should be a diffraction grating.
1) only A
2) only B
4) neither A nor B
Decision.
The diffraction grating gives maxima in the directions given by the condition where is the period of the grating, and is the order of the maximum. As you can see, this condition depends on the wavelength, so light of different frequencies is refracted by a diffraction grating a little differently. This basically makes it possible to see the rainbow spectrum of light.
However, all rays corresponding to a certain maximum and a certain wavelength, after passing through the diffraction grating, propagate parallel to each other, thereby forming a parallel beam of light. Such a parallel beam cannot give a clear image on a nearby screen, so statement A for this optical system turns out to be incorrect. The situation would be saved by a converging lens, which must be positioned so that its focal plane coincides with the screen. As you know, a thin lens collects any parallel beam of light to a point located on the focal plane. However, Statement B proposes to put such a lens in a different way. Thus, we can conclude that B.
Answer: 4.
Answer: 4
Anton
Valentina Gizbrecht 16.06.2016 13:32
The text of the problem says "can be observed", therefore the eyes are included in the scheme of experience. Then why is answer A wrong?
Anton
"observe on the screen»
If you look with your eye, you will see a rainbow, but if you place a screen and look at it, then you will not.
Light with a wavelength of angstroms is incident normally on a diffraction grating. One of the main diffraction maxima corresponds to a diffraction angle of 30°, and the highest order of the observed spectrum is 5. Find the period of this grating.
Reference: 1 angstrom = 10 −10 m.
Decision.
The condition for observing the main maxima for a diffraction grating has the form In this problem, the unknown order of the main maximum corresponds to the diffraction angle, so that where the grating period is unknown and a is an integer.
The highest order of the observed spectrum corresponds to the diffraction angle, so that the grating period is
Substituting this period value into the formula for the order of the diffraction maximum gives the nearest integer greater than this value is 3, so the grating period is
3) If you reduce the wavelength of the incident light, then the distance on the screen between the zero and the first diffraction maxima will decrease.
4) If you replace the lens with another one with a larger focal length and position the screen so that the distance from the lens to the screen is still equal to the focal length of the lens, then the distance on the screen between the zero and the first diffraction maxima will decrease.
5) If we replace the diffraction grating with another one with a longer period, then the angle at which the first diffraction maximum is observed will increase.
Decision.
m. The beam of rays after a thin lens, according to the rules for constructing images in it, is collected at a point in the focal plane of the lens.
d, after it is ok m a parallel beam of light is obtained, going at such an angle that the maximum order order is determined by the relationship:
If we increase the wavelength of the incident light, then the maximum order of the observed diffraction peaks will not increase. 2 is incorrect.
If we reduce the wavelength of the incident light, then according to the basic equation, this will lead to a decrease in the angles and, as a result, the distance between the first and zero maximum on the screen will decrease. 3 is correct.
If we replace the diffraction grating with a grating with a large period, then according to the main equation, this will lead to a decrease in the angles and, as a result, we will observe the first diffraction maximum on the screen at a smaller angle. 5 is incorrect.
Answer: 13.
Which figure correctly shows the relative position of the diffraction grating P, lens L and screen E, in which one can observe the diffraction of a parallel beam of light C?
Decision.
The correct relative position is shown in Figure 4. First, light C must be diffracted in the diffraction grating P. After passing through the grating, the light will go in several parallel beams corresponding to different diffraction maxima. Then it is necessary to collect these parallel beams in the focal plane, this is done by the converging lens L. Finally, it is necessary to put a screen in order to observe focused diffraction maxima on it (in the figure, different diffraction maxima are shown in different colors for convenience).
Answer: 4.
Light with an unknown wavelength is incident normally on a diffraction grating with a period, and one of the main diffraction maxima corresponds to a diffraction angle of 30°. In this case, the highest order of the observed spectrum is 5. Find the wavelength of the light incident on the grating and express it in angstroms.
Reference: 1 angstrom = 10 −10 m.
Decision.
The condition for observing the main maxima for a diffraction grating has the form In this problem, the unknown order of the main maximum corresponds to the diffraction angle so that where the wavelength is unknown, and is an integer.
The highest order of the observed spectrum corresponds to the diffraction angle so that the wavelength is equal to or
Substituting this inequality for the wavelength into the formula for the order of the diffraction maximum, we obtain The nearest integer greater than this value is 3, so the wavelength is
Answer:
Decision.
The minimum distance through which the strokes on the grating are repeated is called the period of the diffraction grating. It can be seen from the figure that on the first and second gratings the strokes are repeated after three divisions, on the third - after two, and on the fourth - after four. Thus, the diffraction grating numbered 4 has the maximum period.
Answer: 4
The figure shows four diffraction gratings. The minimum period has a diffraction grating numbered
Decision.
The minimum distance through which the strokes on the grating are repeated is called the period of the diffraction grating. It can be seen from the figure that on the first and second gratings the strokes are repeated after three divisions, on the third - after two, and on the fourth - after four. Thus, the minimum period has a diffraction grating numbered 3.
Answer: 3
A diffraction grating having 1000 lines per 1 mm of its length is illuminated by a parallel beam of monochromatic light with a wavelength of 420 nm. Light is incident perpendicular to the grating. Close to the diffraction grating, immediately behind it, there is a thin converging lens. Behind the grating at a distance equal to the focal length of the lens, a screen is located parallel to the grating, on which the diffraction pattern is observed. Choose two true statements.
1) The maximum order of observed diffraction maxima is 2.
2) If you increase the wavelength of the incident light, then the maximum order of the observed diffraction maxima will increase.
3) If you reduce the wavelength of the incident light, then the distance on the screen between the zero and the first diffraction maxima will increase.
4) If we replace the lens with another one with a larger focal length and position the screen so that the distance from the lens to the screen is still equal to the focal length of the lens, then the distance on the screen between the zero and the first diffraction maxima will not change.
5) If we replace the diffraction grating with another one with a longer period, then the angle at which the first diffraction maximum is observed from the side of the screen will decrease.
Decision.
First, let us plot the path of parallel rays from the source passing through the diffraction grating and lens to the screen, where a spectrum of the order m(for some one spectral line of mercury with a wavelength ). The beam of rays after a thin lens, according to the rules for constructing images in it, is collected at a point in the focal plane of the lens.
According to the basic equation for the angles of deflection of light with a wavelength by a grating with a period d after that it's ok m a parallel beam of light is obtained, going at such an angle that the maximum order order will be observed at:
If we increase the wavelength of the incident light, then the maximum order of the observed diffraction maxima will not change or decrease. 2 is incorrect.
If we reduce the wavelength of the incident light, then this will lead to a decrease in the angle between the zero and first diffraction maxima and, as a consequence, to a decrease in the distance between the zero and the first maximum on the screen. 3 is incorrect.
According to the rules for constructing rays in a converging lens, a lens with a large focal length will increase the distance between the zero and the first maximum. 4 is incorrect.
If we replace the diffraction grating with a grating with a long period, this will lead to a decrease in the angle at which the first diffraction maximum is observed. 5 is correct.
Answer: 15.
Five experiments were carried out in the laboratory to observe diffraction using various diffraction gratings. Each of the gratings was illuminated by parallel beams of monochromatic light with a certain wavelength. The light in all cases was incident perpendicular to the grating. First indicate the number of the experiment in which the smallest number of main diffraction maxima was observed, and then the number of the experiment in which the largest number of main diffraction maxima was observed.
| Number experiment | Diffraction period | Wavelength incident light |
|---|---|---|
| 1 | 2d | |
| 2 | d | |
| 3 | 2d | |
| 4 | d/2 | |
| 5 | d/2 |
Decision.
The condition of the interference maxima of the diffraction grating has the form: In this case, the more the less diffraction maxima will be visible. Thus, the smallest number of main diffraction maxima was observed in experiment number 5, and the largest - in experiment number 1.
Answer: 51.
Answer: 51
Source: Training work in physics 04/28/2017, variant PHI10504
A monochromatic beam of light falls normally on a diffraction grating with a period, and behind the grating there is an objective, in the focal plane of which diffraction maxima are observed (see figure). The dots show the diffraction peaks, and the numbers indicate their numbers. The diffraction angles are small.
This diffraction grating is alternately replaced by other diffraction gratings - A and B. Establish a correspondence between the patterns of diffraction maxima and the periods of the diffraction gratings used.
| SCHEME OF DIFFRACTION MAXIMUMS | DIFFRACTION GRATING PERIOD | |
| A | B |
