Module 6: Current, Resistance, and Ohm's Law

Question 1

Answer 1

vd/4

Question 2

Two cables of the same length are made of the same material, except that one cable has twice the diameter of the other cable. When the same potential difference is maintained across both cables, which of the following statements are true?

1. The same current flows through both cables.
2. Both cables carry the same current density.
3. The current in the thin cable is twice as great as the current in the thick cable.
4. The current in the thin cable is four times as great as the current in the thick cable.

Answer 2

2. Both cables carry the same current density.

Question 3

Copper wire #1 has a length L and a radius b. Copper wire #2 has a length of 2L and a radius of 2b. Which statement is true?

1. The total resistance of wire #1 is half that of wire #2.
2. The total resistance of wire #1 is four times higher than that of wire #2.
3. The total resistance of wire #1 is twice as high as that of wire #2.
4. The total resistance of wire #1 is equal to that of wire #2.

Answer 3

3. The total resistance of wire #1 is twice as high as that of wire #2.

Question 4

A current flowing through a copper wire (which is connected to a battery) is due to

Answer 4

electrons being accelerated by an electric field.

Question 5

A copper wire of length L and radius b is attached to another copper wire of length L and radius 2b, forming one long wire of length 2L. This long wire is attached to a battery, and a current is flowing through it. Relative to the electric field within the wire of radius b, the magnitude of the electric field within the wire of radius 2b is x times stronger, weaker, or equal?

Answer 5

four times weaker.

Question 6

If the length and diameter of a wire of circular cross-section are both doubled, the resistance is

Answer 6

halved

Question 7

Current flows through a resistor in what direction?

Answer 7

from high potential to low potential.

Question 8

Which of the following cylindrical wires has the largest resistance? All wires are made of the same material.

1. a wire of length L/2 and diameter 2d
2. a wire of length L/2 and diameter d
3. a wire of length L and diameter d/2
4. a wire of length L and diameter 2d
5. a wire of length L and diameter d

Answer 8

3. a wire of length L and diameter d/2

Question 9

How much energy does a 100-W light bulb use in 8.0 hours?

Answer 9

0.80 kWh

Question 10

1. The drift velocity decreases from A to B and increases from B to C.
2. The drift velocity increases from A to B and decreases from B to C.
3. The drift velocity remains constant.
4. The drift velocity increases all the time.
5. The drift velocity decreases all the time.

Answer 10

2. The drift velocity increases from A to B and decreases from B to C.