Module 12 Quiz

Question 1

A small “package” of light that acts like a particle

Answer 1

Photon

Question 2

Charging an object by allowing it to come into contact with an object that already has an electrical charge

Answer 2

Charging by conduction

Question 3

Charging an object without direct contact between the object and a charge

Answer 3

Charging by induction

Question 4

The amount of charge that travels past a fixed point in an electric circuit each second

Answer 4

Electrical current

Question 5

Current that flows from the positive side of the battery to the negative side. This is the way current is drawn in circuit diagrams, even though it is wrong.

Answer 5

Conventional current

Question 6

The ability of a material to impede the flow of charge

Answer 6

Resistance

Question 7

A circuit that does not have a complete connection between the two sides of the power source. As a result, current does not flow.

Answer 7

Open circuit

Question 8

The force between the south pole of a magnet and the north pole of another magnet is measured. If the distance between the poles is increased by a factor of 3, how does the new force compare to the old one? Is the force attractive or repulsive?

Answer 8

The electromagnetic force is inversely proportional to the square of the distance between the objects. Thus, if the distance is multiplied by 3, the force is divided by 9. Since the poles are opposite, it is an attractive force.

Question 9

Two charged particles are placed 10 centimeters from each other and the resulting force is measured. The charge on object #1 is then doubled and the charge on object #2 is left the same. Also, the distance between the objects is reduced to 5 centimeters. How does the new force compare to the old force?

Answer 9

The electromagnetic force is directly proportional to the charge. When the first charge is doubled, the force is doubled. Since the second charge is left the same, there is no change with respect to that charge. The force varies inversely with the square of the distance between objects. Thus, if the distance is divided by 2, the force is multiplied by 4. The total change, then, is 2 x 4 = 8. The new force is 8 times stronger than the old one.

Question 10

What causes the electromagnetic force?

Answer 10

The exchange of photons causes the electromagnetic force.

Question 11

Given your answer to question #5, why don’t charged particles glow?

Answer 11

Charged particles do not glow because the photons they emit are not visible to you and me. Under the right conditions, however, charged particles can emit visible light. At those times, you could say that the charged particles do “glow.”

Question 12

If you were to use a positively charged rod to charge an object by induction, what charge will the object have?

Answer 12

Charging by induction results in a charge opposite of the rod. Thus, the object will be negatively charged.

Question 13

If you were to use a positively charged rod to charge an object by conduction, what charge will the object have?

Answer 13

Charging by conduction results in the same charge as the rod. Thus, the object will be positively charged.

Question 14

An electrical circuit uses a large voltage but a small current. Is the energy of each electron high or low? Are there many electrons flowing through the circuit, or are there few? Is the circuit dangerous?

Answer 14

Voltage tells us how hard the electricity source pushes on the electrons. This means the larger the voltage, the higher the energy of each electron. Thus, each electron has high energy. Current refers to how many electrons flow through the circuit. Thus, few electrons flow through the circuit. Even though there are few electrons, they each have high energy. Thus, the circuit could be dangerous.

Question 15

Under what conditions is an electrical circuit reasonably safe?

Answer 15

A circuit is reasonably safe when both the voltage and the current are low. Please realize that “low” is a relative term. A low voltage is 9 volts or less. A low current is 0.001 Amps or less.

Question 16

What is wrong with conventional current?

Answer 16

Conventional current assumes that electricity is the flow of positive charges. We know, however, that electricity is the flow of electrons, which are negative.

Question 17

You have two wires. One is long and the other is short. Other than that, they are identical. Which has more resistance?

Answer 17

The longer the wire, the more chances the electrons have for colliding with atoms within the wire. Thus, the longer wire has more resistance.

Question 18

You have two wires. One is thin, and the other is very thick. When the same current is run through each wire, which will get hotter?

Answer 18

The wider, or thicker, the wire, the more the electrons can spread out. This means there is less likelihood of electrons colliding with atoms in the wire. Thus, the thicker wire will have less resistance. For the same amount of current, less resistance means less heat. Thus, the thin wire will get hotter. This is one of the causes of house fires. A person uses too thin an extension cord and tries to allow it to run too many devices. This draws too much current for the thin wire, heating it up to the point that it causes a fire.

Question 19

Three lights are in a circuit. When one burns out, they all go out. When the burnt-out one is replaced with a good light, the other two lights work again. Are the lights wired in a parallel circuit or a series circuit?

Answer 19

The bulbs are wired in a series circuit, because a burnt-out bulb acts like an open switch. If the open switch turns off the bulbs, it is wired in series with the other bulbs.

Question 20

If it takes a flow of charged particles to make a magnet, where is the charged particle flow in a permanent magnet?

Answer 20

In a permanent magnet, the flow of charged particles is the motion of the electrons in its atoms.

Question 21

Is it possible to have a permanent magnet with only a north pole?

Answer 21

As far as we know, this is not possible. Magnets must always have both a north and south pole.

Question 22

Is it possible to make a magnet from something that is not a magnet?

Answer 22

Yes, it is possible. If the material responds strongly enough to a magnet, you can align its atoms and make it a magnet.

Question 23

If a material does not respond to a magnet, what can you conclude about the atoms in that material?

Answer 23

If a material is not magnetic, its atoms cannot be aligned. As a result, the flow of electrons is random, and the material cannot respond to a magnet.

Question 24

Study #2, 11, & 15 on CD

Answer 24

Study #2, 11, & 15 on CD