Dear students of 8th grade!
On Saturday, you and I had a special course lesson, which you will also need to work on at home. I offer you a small space quiz (30 questions), 3 tests and 5 Olympiad problems. Quiz and test questions must be answered All students, Send me the answers by email by Friday! Olympiad tasks are written in a workbook. I will check them along with other entries, and if you solve them correctly, I will rate them with a separate mark. Don’t forget to submit your answers to the test on the topic “Electric Current.”
Good luck! Don't be bored, don't get sick, your E.V.
Space quiz.
1. How can you call in one word the gas shell surrounding a celestial body?
2. The main cosmodrome from which the first spaceships launched?
3. One of the 9 planets in the solar system. In ancient mythology, the mother of Cupid, the goddess of love
4. Who said: “Having flown around the Earth in a satellite ship, I saw how beautiful our planet is. People, let us preserve and increase this beauty, and not destroy it.”
5. Full name chief designer of the first Soviet space rockets.
6. The place where they prepare for flight into space and from where rockets and devices are launched.
7. In one word, you can call a person whom doctors select; he must be widely educated; he undergoes several years of radio engineering training, various kinds of tests and training.
8. The second Soviet satellite was launched a month after the first; there was (who?) on board, who did not return from space.
9. A satellite of the Earth, facing the same side.
10. One of the planets of the solar system, similar to the Moon, dust storms of terrible force rage on it; in mythology, it is the god of war.
11. This is the planet closest to the Sun, the surface temperature on the shadow side is 185 degrees, on the solar side + 510 degrees, in mythology - the god of trade.
12. The only planet with strong own radio emission, in mythology - the god of daylight and thunderstorms.
13. What was the call sign of the first cosmonaut?
14. Who was the backup on the first flight?
15. What was the name of the spaceship on which it flew?
16. What is the name of a space station that operated in orbit for many years and recently ceased to exist?
17. Who was the chief designer of the spacecraft he flew on?
18. What is the name of the space gear that an astronaut wears?
19. What were the names of the dogs who were the first to go into space and return to Earth?
20. What animals did the Americans launch into space instead of dogs?
21. How many days did the first artificial Earth satellite exist in orbit?
22. What was the name of the ship on which Gagarin flew into space?
23. How many women have been in space?
24. How is the Universe different from space?
25. What is the maximum theoretically possible duration of a solar eclipse?
26. Which famous astronaut said: “I wasn’t in space, I worked there”?
27. The average distance to which astronomical object is called an astronomical unit?
28. What is Space Europe?
29. What are the names of Indian astronauts?
30. What happens if a red giant (star) sheds its shell?
Test 1. Electrification of bodies. Electric field. Atomic structure
1 . When rubbed against silk, the glass charges...
A. positive. B. negative.
2. If an electrified body is repelled by an ebonite stick rubbed against fur, then it...
A. has no charge. B. is positively charged.
V. is negatively charged.
3.
The picture shows light balls suspended on silk threads. Which of the figures corresponds to the case when the balls have the same charges?
A.1. B.2.
4. A stick rubbed with fur is brought to the ball. What is the sign of the charge on the ball?
A. Positive. B. Negative.
5.
How will a metal body A be charged if a charged body B is brought to it?
A. Positive.
B. Negative.
B. Neutral.
6
. What kind of rod - glass, ebonite or steel - should be used to connect the electroscopes so that they are both charged?
A. Glass. B. Ebonitov. V. Steel.
7 . The copper rod, which had a positive charge, was discharged and became electrically neutral. Will the mass of the rod change?
A. It won't change. B. Will increase. B. Will decrease.
8 . Which particle has the least negative electrical charge?
A. Electron. B. Neutron. B. Proton.
9.
The figure shows a diagram of a lithium atom. Is this atom charged?
A. The atom is negatively charged.
B. The atom is positively charged.
B. The atom is electrically neutral.
10. Which chemical element is shown schematically in the picture?
A. Hydrogen. B. Lithium. ‘ V. Helium.
Test 2: Melting and solidification.
1 When a solid melts, its temperature...
A. does not change. B. increases. V. decreases.
2 The specific heat of melting of ice is 3.4*105 J/kg. It means that
A. To melt 1 kg of ice, 3.4 * 105 J/kg of heat is required.
B. melting 3.4*105 kg of ice requires 1 J of heat.
B. when melting 1 kg of ice, 3.4 * 105 J of heat is released.
3. Which metal, when in a molten state, can freeze water?
A. Lead. B. Tin. B. Mercury.
4. What can be said about the internal energy of a molten and unmolten piece of copper weighing 1 kg at a temperature of 1085 ° C?
A. Their internal energies are the same.
B. The internal energy of a molten piece of copper is greater.
B. The internal energy of a molten piece of copper is less.
5. What energy is required to melt 1 kg of ice taken at its melting point?
A. 3.4*105J. B. 0.25 *105J C. 2 *105J
6. Calculate the amount of heat required to melt 2 kg of lead at a temperature of 227 °C
A. 5*107 J. B. 0.78*105 J. B. 0.5*107 J.
7. What amount of heat will be released during crystallization and cooling of 4 kg of copper to a temperature of 585 °C?
A. 5000 kJ. B. 3200 kJ. V. 1640 kJ.
8. Figure 42 shows a graph of cooling and crystallization of a solid. Which process does the section of the BC graph correspond to?
A. Cooling. B. Melting. B. Crystallization.
9. For which substance is the melting and heating graph shown (Fig. 43)?
A. Ice. B. Tin. V. Zinc.
10. Determine from the graph (see Fig. 43) how much heat is required to heat and melt 2 kg of solid substance.
A. 400 kJ. B. 890 kJ. B. 1200 kJ.
Test 3. Evaporation and boiling
1. Evaporation occurs...
A. at any temperature.
B. at boiling point.
B. at a specific temperature for each liquid.
2. As the temperature of the liquid increases, the evaporation rate...
A. decreases.
B. increases.
V. does not change.
3. In the presence of wind, evaporation occurs...
A. faster.
B. slower.
V. at the same speed as in its absence.
4 The formation of steam during boiling occurs..., and during evaporation...
A. on the surface of the liquid; inside and on the surface of the liquid.
B. inside the liquid; on the surface of the liquid.
B. inside and on the surface of the liquid; on the surface of the liquid.
5. Compare the internal energies of 1 kg of one hundred degree water vapor and 1 kg of water at the same temperature.
A. The internal energies are equal.
B. The internal energy of water vapor is greater.
B. The internal energy of water is greater.
6. How much energy will be released during the condensation of 200 g of alcohol taken at a temperature of 78 ° C?
A. 0.18 106 J. B. 2 104 J. B. 3 106 J.
7. What amount of heat is required to convert 100 g of ether at a temperature of 5 0C into steam?
A.J.B.J. V.J
8. Figure 46 shows a graph of liquid cooling and condensation. Which process does the section of the BC graph correspond to?
A. Heating. B. Cooling. B. Condensation .
9. For which substance is the heating and boiling graph shown (Fig. 47)?
A. Ether. B. Water. B. Alcohol.
10. Determine from the graph (see Fig. 47) how much heat is required to heat and turn 2 kg of substance into steam.
A. 1950 kJ. B. 2500 kJ. B. 500 kJ.
Olympic tasks.
1 .Calculate the volume of a cork belt that should be 90% immersed in water when used by a person weighing 50 kg. Cork density is 200 kg/m³. The density of water is 1000 kg/m³.
2 A passenger, while on a train traveling at a speed of 36 km/h, determined that the oncoming train, consisting of 12 cars, each 24 m long, passed by him in 9 seconds. Determine the speed of the oncoming train: a) relative to the passenger; b) relative to the ground.
3 . An alloy of gold and silver with a density of 1.40 × 104 kg/m3 has a mass of 0.40 kg. Determine the mass and percentage of gold in the alloy, counting the volume of the alloy equal to the sum of the volumes of its constituent parts.
4 . The weight of a homogeneous body in water is three times less than in air. What is the density of the body if the density of water is 103 kg/m3?
5 . It is known that if the temperature outside is –20 °C, then the temperature in the room is +20 °C, and if the temperature outside is –40 °C, then the temperature in the room is +10 °C. Find the temperatureTradiators heating the room.
The word electricity comes from the Greek name for amber - ελεκτρον
.
Amber is the fossilized resin of coniferous trees. The ancients noticed that if you rub amber with a piece of cloth, it will attract light objects or dust. This phenomenon, which we today call static electricity, can be observed by rubbing an ebonite or glass rod or simply a plastic ruler with a cloth.
A plastic ruler, which has been thoroughly rubbed with a paper napkin, attracts small pieces of paper (Fig. 22.1). You may have seen discharges of static electricity while combing your hair or taking off your nylon blouse or shirt. You may have experienced an electrical shock when you touched a metal door handle after standing up from a car seat or walking on synthetic carpet. In all these cases, the object acquires an electrical charge through friction; they say that electrification occurs by friction.
Are all electric charges the same or are there different types? It turns out that there are two types of electric charges, which can be proven by the following simple experiment. Hang a plastic ruler by the middle on a thread and rub it thoroughly with a piece of cloth. If we now bring another electrified ruler to it, we will find that the rulers repel each other (Fig. 22.2, a).
In the same way, bringing another electrified glass rod to one, we will observe their repulsion (Fig. 22.2,6). If a charged glass rod is brought to an electrified plastic ruler, they will be attracted (Fig. 22.2, c). The ruler appears to have a different kind of charge than the glass rod.
It has been experimentally established that all charged objects are divided into two categories: either they are attracted by plastic and repelled by glass, or, conversely, repelled by plastic and attracted by glass. There appear to be two kinds of charges, charges of the same kind repel, and charges of different kinds attract. We say that like charges repel, and unlike charges attract.
The American statesman, philosopher and scientist Benjamin Franklin (1706-1790) called these two types of charges positive and negative. It made absolutely no difference what charge to call;
Franklin proposed that the charge of an electrified glass rod be considered positive. In this case, the charge appearing on the plastic ruler (or amber) will be negative. This agreement is still followed today.
Franklin's theory of electricity was in effect a "one fluid" concept: a positive charge was seen as an excess of the "electrical fluid" over its normal content in a given object, and a negative charge as a deficiency. Franklin argued that when, as a result of some process, a certain charge arises in one body, the same amount of charge of the opposite kind simultaneously arises in another body. The names “positive” and “negative” should therefore be understood in an algebraic sense, so that the total charge acquired by bodies in any process is always equal to zero.
For example, when a plastic ruler is rubbed with a paper napkin, the ruler acquires a negative charge, and the napkin acquires an equal positive charge. There is a separation of charges, but their sum is zero.
This example illustrates the firmly established law of conservation of electric charge, which reads:
The total electric charge resulting from any process is zero.
Deviations from this law have never been observed, therefore we can consider that it is as firmly established as the laws of conservation of energy and momentum.
Electric charges in atoms
Only in the last century did it become clear that the reason for the existence of electric charge lies in the atoms themselves. Later we will discuss the structure of the atom and the development of ideas about it in more detail. Here we will briefly discuss the main ideas that will help us better understand the nature of electricity.
According to modern concepts, an atom (somewhat simplified) consists of a heavy positively charged nucleus surrounded by one or more negatively charged electrons.
In the normal state, the positive and negative charges in an atom are equal in magnitude, and the atom as a whole is electrically neutral. However, an atom can lose or gain one or more electrons. Then its charge will be positive or negative, and such an atom is called an ion.
In a solid, nuclei can vibrate, remaining near fixed positions, while some electrons move completely freely. Electrification by friction can be explained by the fact that in different substances the nuclei hold electrons with different strengths.
When a plastic ruler that is rubbed with a paper napkin acquires a negative charge, this means that the electrons in the paper napkin are held less tightly than in the plastic, and some of them transfer from the napkin to the ruler. The positive charge of the napkin is equal in magnitude to the negative charge acquired by the ruler.
Typically, objects electrified by friction only hold a charge for a while and eventually return to an electrically neutral state. Where does the charge go? It “drains” onto the water molecules contained in the air.
The fact is that water molecules are polar: although in general they are electrically neutral, the charge in them is not uniformly distributed (Fig. 22.3). Therefore, excess electrons from the electrified ruler will “drain” into the air, being attracted to the positively charged region of the water molecule.
On the other hand, the positive charge of the object will be neutralized by electrons, which are weakly held by water molecules in the air. In dry weather, the influence of static electricity is much more noticeable: there are fewer water molecules in the air and the charge does not flow off as quickly. In damp, rainy weather, the item is unable to hold its charge for long.
Insulators and conductors
Let there be two metal balls, one of which is highly charged and the other is electrically neutral. If we connect them with, say, an iron nail, the uncharged ball will quickly acquire an electric charge. If we simultaneously touch both balls with a wooden stick or a piece of rubber, then the ball, which had no charge, will remain uncharged. Substances such as iron are called conductors of electricity; wood and rubber are called non-conductors, or insulators.
Metals are generally good conductors; Most other substances are insulators (however, insulators conduct electricity a little). Interestingly, almost all natural materials fall into one of these two sharply different categories.
There are, however, substances (among which silicon, germanium and carbon should be mentioned) that belong to an intermediate (but also sharply separated) category. They are called semiconductors.
From the point of view of atomic theory, electrons in insulators are bound to nuclei very tightly, while in conductors many electrons are bound very weakly and can move freely within the substance.
When a positively charged object is brought close to or touches a conductor, free electrons quickly move toward the positive charge. If an object is negatively charged, then electrons, on the contrary, tend to move away from it. In semiconductors there are very few free electrons, and in insulators they are practically absent.
Induced charge. Electroscope
Let's bring a positively charged metal object to another (neutral) metal object.
Upon contact, free electrons of a neutral object will be attracted to a positively charged one and some of them will transfer to it. Since the second object now lacks a certain number of negatively charged electrons, it acquires a positive charge. This process is called electrification due to electrical conductivity.
Let us now bring the positively charged object closer to the neutral metal rod, but so that they do not touch. Although the electrons will not leave the metal rod, they will nevertheless move towards the charged object; a positive charge will arise at the opposite end of the rod (Fig. 22.4). In this case, it is said that a charge is induced (or induced) at the ends of the metal rod. Of course, no new charges arise: the charges simply separated, but on the whole the rod remained electrically neutral. However, if we were now to cut the rod crosswise in the middle, we would get two charged objects - one with a negative charge, the other with a positive charge.
You can also impart a charge to a metal object by connecting it with a wire to the ground (or, for example, to a water pipe going into the ground), as shown in Fig. 22.5, a. The subject is said to be grounded. Due to its enormous size, the earth accepts and gives up electrons; it acts as a charge reservoir. If you bring a charged, say, negatively, object close to the metal, then the free electrons of the metal will be repelled and many will go along the wire into the ground (Fig. 22.5,6). The metal will be positively charged. If you now disconnect the wire, a positive induced charge will remain on the metal. But if you do this after the negatively charged object is removed from the metal, then all the electrons will have time to return back and the metal will remain electrically neutral.
An electroscope (or simple electrometer) is used to detect electrical charge.
As can be seen from Fig. 22.6, it consists of a body, inside of which there are two movable leaves, often made of gold. (Sometimes only one leaf is made movable.) The leaves are mounted on a metal rod, which is insulated from the body and ends on the outside with a metal ball. If you bring a charged object close to the ball, a separation of charges occurs in the rod (Fig. 22.7, a), the leaves turn out to be similarly charged and repel each other, as shown in the figure.
You can completely charge the rod due to electrical conductivity (Fig. 22.7, b). In any case, the greater the charge, the more the leaves diverge.
Note, however, that the sign of the charge cannot be determined in this way: a negative charge will separate the leaves exactly the same distance as an equal positive charge. And yet, an electroscope can be used to determine the sign of the charge; for this, the rod must first be given, say, a negative charge (Fig. 22.8, a). If you now bring a negatively charged object to the electroscope ball (Fig. 22.8,6), then additional electrons will move to the leaves and they will move apart further. On the contrary, if a positive charge is brought to the ball, then the electrons will move away from the leaves and they will come closer (Fig. 22.8, c), since their negative charge will decrease.
The electroscope was widely used at the dawn of electrical engineering. Very sensitive modern electrometers operate on the same principle when using electronic circuits.
This publication is based on materials from the book by D. Giancoli. "Physics in two volumes" 1984 Volume 2.
To be continued. Briefly about the following publication:
Force F, with which one charged body acts on another charged body, is proportional to the product of their charges Q 1 and Q 2 and inversely proportional to the square of the distance r between them.
Comments and suggestions are accepted and welcome!
948. The ball is positively charged. The student touched it with his finger. How did the ball's charge change?
The charge will go into the ground through the student’s body.
949. A metal sphere has a charge of -1.6 nC. How many excess electrons are there on the sphere?
950. After the glass rod was rubbed, its charge became 3.2 µC. How many electrons were removed from the stick by friction?
951. There are 4.8 1010 excess electrons on a metal ball. What is its charge?
952. The electroscope was charged to -3.2 10-10 C. How many excess electrons are there in the electroscope?
953. Is it possible to electrify a piece of metal? What conditions are necessary for this?
It is possible by influencing it with an electric field.
954. With mutual friction, both bodies are electrified, but with charges of the opposite sign. What experience can demonstrate this?
If you rub dry cloth on an ebonite stick, the stick is attracted to the cloth.
955. Two identical cork balls are suspended on thin silk threads, one charged, the other uncharged. How to determine which ball is charged?
Bring an electrified ebonite stick to the balls. The charged ball will be attracted or repelled from it.
956. Two charges of different sizes are located at a certain distance from each other. A third charge of the same sign is placed between them, which remains in equilibrium. Which of the two charges is the third closest to?
The third charge is closer to the smaller charge, i.e. from more he is repelled more strongly.
957. How can we explain that a light cork ball is first attracted to an electrified stick and then repelled from it?
A ball in an electrostatic field is polarized. An opposite charge is concentrated on the surface and the ball is attracted to the stick. After contact, part of the charge transfers to the ball, which receives a charge of the same sign and is repelled from the stick.
958. Between two horizontal oppositely charged plates an uncharged drop of water hangs in the air (Fig. 88). Why doesn't the drop fall down?
An electrostatic force acts on the drop, opposite to the direction of gravity.
959. The electronic theory states that only electrons - negative charges - can move freely in metal conductors. Then how can we explain that a metal object can be positively charged?
The positive charge can be explained by a lack of electrons.
960. Figure 89 shows two oppositely charged bodies A and B. A light, positively charged ball a was placed near body A. What will happen to ball a? Draw a curve along which ball a will move.
961. Why is an uncharged elderberry bead attracted to both a positively and negatively charged bead?
A charge opposite in sign to the charged ball is concentrated on the uncharged ball and the ball is attracted to it.
962. Why, when holding it in your hand, can you electrify a plastic comb by friction, but not a metal comb?
Because plastic is a dielectric and metal is a conductor.
963. Why is it impossible to electrify a metal rod by friction, even if you touch a charged body with this rod?
Because the charge will immediately go through the body into the ground.
964. If a body with an opposite charge is brought to the charged ball of an electroscope without touching the ball, the leaves of the electroscope will move closer together. Why?
Part of the charge from the leaves will transfer to the electroscope ball under the influence of electrostatic forces.
965. If you touch the ball of a charged electroscope with your hand, the electroscope discharges. Why?
The charge will pass through the human body into the ground.
966. When a hand is brought to the ball of a charged electroscope without touching the ball, the leaves of the electroscope come closer. Why?
A charge is concentrated on the hand, opposite in sign to the charge of the electroscope, and part of the charge from the leaves passes into the ball.
967. A positively charged rod is brought to the ball of an uncharged electroscope (without touching the ball). What charge is obtained on the leaves of the electroscope?
A negative charge will appear on the surface of the ball, and a positive charge on the leaves.
968. Balls A and B are oppositely charged. A positively charged small ball placed between them moves towards body B. Which of the balls is positively charged?
Ball B is negatively charged, ball A is positively charged.
969. Why is the rod of an electroscope made of metal?
So that the charge from the ball is transferred to the leaves.
970. In order for the electroscope to more accurately show the magnitude of the charge, it is grounded - its outer surface is connected to the ground (Fig. 90). Why is this being done?
So that there is no charge on the body of the electroscope.
972. Why does an electrified glass rod attract light objects: pieces of paper, corks, elderberry balls, etc.?
Opposite charges are concentrated on the surface of these bodies and will attract each other.
973. How to determine the sign of a body’s charge using an electroscope?
Touch the electroscope ball with a charged body, then bring the charged body whose charge sign is known. If the leaves go down, the charges are different.
974. Why is it difficult, and sometimes almost impossible, to charge an electroscope at high air humidity?
The charge leaves the electroscope through moisture particles.
975. It is known that if a charged metal ball is touched uncharged, then after separation both balls turn out to be charged. However, when a charged ball is connected to the ground, it is almost completely discharged. Why?
Most of the charge goes to the larger body. The size of the Earth is incommensurably larger than any body located on it.
976. Why are excess charges in conductors located only on the surface?
The electrons repel each other and are distributed so that the field strength inside is minimal.
977. A negatively charged body is brought to the ball of an uncharged electroscope (without touching it). Determine the signs of the charges on the ball and on the leaves of the electroscope.
A positive charge appears on the ball, and a negative charge on the leaves.
978. Two uncharged electroscopes are connected to each other by a metal wire (Fig. 91). A positively charged stick was brought to the ball of one (without touching it). What charges will be on the balls and leaves of each electroscope?
On the right electroscope: on the ball “-” on the leaves “+”; on the left electroscope: on the ball “+” on the leaves “-”.
979. The charged rod was removed from the electroscopes of the previous problem. What happened to the leaves of both electroscopes?
The leaves will fall.
980. What needs to be done to ensure that electroscopes (see Fig. 91) remain charged after the rod is removed?
Cut the metal wire.
981. If the electroscopes (see Fig. 91) remained charged after the rod was removed, then what sign of the charges will appear on the balls and leaves of each electroscope?
Left is negative, right is positive.
982. Answer the questions of problems 969-972 for the case when an ebonite rod rubbed on fur is brought to the electroscope.
The stick will have a negative charge. All charges will change to positive.
983. To electrify an electroscope positively, a negatively electrified rod is brought closer to the ball. Then, without removing the sticks, touch the ball with your hand for a moment. After this, the stick is removed and the electroscope is charged.
Do this experiment and explain it.
The negative charge of the stick will change the positive charge from the hand to the ball.
984. Charge the electroscope negatively in the same way. What charge and what rod should be electrified for this and brought to the electroscope? Explain this process based on electron theory.
You need to bring a positively charged stick to it, then touch the ball with your hand for a moment. The positive charge of the stick will transfer the negative charge from the hand to the ball.
985. An insulated metal cylinder is connected to an electroscope. The presence of what charges will be shown by the electroscope in the following cases:
a) a positively charged ball is introduced into the cylinder without being in contact with it;
b) the charged ball is touched to the inner surface of the cylinder;
c) the ball is inserted inside the cylinder (without touching it), then they touch the cylinder with their hand, remove their hand and remove the ball from the cylinder?
A) positive
B) positive if the ball is positively charged.
B) negative if the ball was positively charged.
986. In what cases can a lightning rod pose a danger to a building?
If the lightning rod is not grounded.
Option 1.
1 . When rubbed against silk, the glass charges...
2 . If an electrified body is repelled by an ebonite stick rubbed against fur, then it...
A. has no charge.
B. is positively charged.
B. negatively charged.
3 . The picture shows light balls suspended on silk threads. Which of the figures corresponds to the case when the balls have the same charges?
A. 1. B. 2.
4 . A stick rubbed on fur is brought to the ball (fig). What is the sign of the charge on the ball?
A. Positive. B. Negative.
5 . How will metal body A be charged if a charged body B is brought to it (fig)?
A. Positive.
B. Negative.
B. Neutral.
6 . What kind of rod - glass, ebonite or steel - should be used to connect the electroscopes so that they are both charged (fig)?
A. Glass. B. Ebonitov. V. Steel.
7 . The copper rod, which had a positive charge, was discharged and became electrically neutral. Will the mass of the rod change?
A. It won't change. B. Will increase. B. Will decrease.
8 . Which particle has the least negative electrical charge?
A. Electron. B. Neutron. B. Proton.
9 . The figure shows a diagram of a lithium atom. Is this atom charged?
10 . Which chemical element is shown schematically in the figure?
Test work in 8th grade physics. Topic: Electrification of bodies. The structure of the atom.
Option 2.
1 . When an ebonite stick is rubbed against fur, it charges...
A. positive. B. negative.
2 . If an electrified body is attracted to a glass rod rubbed on silk, then it...
A. positively charged.
B. is negatively charged.
V. has no charge.
3 . The picture shows balls suspended on silk threads. Which picture shows balls charged with opposite charges?
A. 1. B. 2.
4 . A glass rod rubbed on silk (rice) is brought to the elderberry ball. What is the sign of the charge on the ball?
A. Negative. B. Positive.
5 . Which of the charged bodies is affected by the charged ball (fig) with less force?
A. 1. B. 2. C. 3.
6 . What kind of rod - copper, ebonite or steel - are the electroscopes connected to (fig)?
A. Medny. B. Ebonitov. V. Steel.
7 . The iron ball, which had a negative charge, was discharged and it became electrically neutral. Will the mass of the ball change?
A. It won't change. B. Will increase. B. Will decrease.
8 . What particles make up the nucleus of an atom?
A. Electrons and protons.
B. Neutrons and protons.
B. Electrons and neutrons.
9 . The figure shows a diagram of a hydrogen atom. Is this atom charged?
A. The atom is negatively charged.
B. The atom is positively charged.
B. The atom is electrically neutral.
10 . Which chemical element is shown schematically in the picture?
A. Hydrogen. B. Lithium. B. Helium.