Question 1

Which of the following best describes the direction of conventional current in a metal wire connected to a battery?

Accepted Answer

From higher potential to lower potential, in the direction of the electric field.

Question 2

A wire carries a current of $$2\ \mathrm{A}$$ for $$3\ \mathrm{minutes}. $$How much charge passes through the wire in this time?

Accepted Answer

$$360\ \mathrm{C}$$

Question 3

Which equation correctly defines electric current $$I in $$terms of charge $$\Delta q$$ and time interval $$\Delta t$$?

Accepted Answer

$$I = \frac{\Delta q}{\Delta t}$$

Question 4

A battery is connected to a lightbulb. If the potential difference across the bulb is doubled, what happens to the current through the bulb (assuming resistance is constant)?

Accepted Answer

The current doubles.

Question 5

Which of the following statements about resistance is correct?

Accepted Answer

Resistance is inversely proportional to the wire's cross-sectional area.

Question 6

A wire has a resistance $$R. If $$both its length and diameter are doubled, what happens to its resistance?

Accepted Answer

It remains the same.

Question 7

Which equation gives the resistance $$R of a $$wire in terms of its resistivity $$\rho$$, length $$L$$, and cross-sectional area $$A$$?

Accepted Answer

$$R = \frac{\rho L}{A}$$

Question 8

A junction in a circuit has three wires carrying currents of $$2\ \mathrm{A} in$$, $$3\ \mathrm{A} in$$, and $$4\ \mathrm{A}$$ out. What is the magnitude and direction of the current in the fourth wire?

Accepted Answer

$$1\ \mathrm{A} in$$

Question 9

A battery rated at $$1.5\ \mathrm{V} is $$connected in series with two other identical batteries. What is the total potential difference across all three batteries?

Accepted Answer

$$4.5\ \mathrm{V}$$

Question 10

A copper wire and an aluminum wire have the same length and cross-sectional area. Which has the lower resistance and why?

Accepted Answer

The copper wire, because copper has a lower resistivity.

Question 11

A lightbulb is connected to a battery. If the filament of the bulb is made thinner, what happens to the brightness of the bulb and why?

Accepted Answer

It becomes dimmer because resistance increases.

Question 12

Which of the following best describes the role of a battery in a circuit?

Accepted Answer

It acts as a charge escalator, maintaining a potential difference.

Question 13

A wire has a current of $$I = 5\ \mathrm{A}$$ when a potential difference of $$\Delta V = 10\ \mathrm{V} is $$applied. What is the resistance of the wire?

Accepted Answer

$$2\ \Omega$$

Question 14

If $$120\ \mathrm{C} of $$charge flows through a wire in $$1\ \mathrm{minute}$$, what is the current?

Accepted Answer

$$2\ \mathrm{A}$$

Question 15

Which of the following is a correct statement of Kirchhoff’s junction law?

Accepted Answer

The sum of the currents entering a junction equals the sum leaving.

Question 16

A wire has a resistivity $$\rho$$, length $$L$$, and cross-sectional area $$A. If $$the length is doubled and the area is halved, what happens to the resistance?

Accepted Answer

It becomes four times larger.

Question 17

Which of the following materials would make the best electrical conductor?

Accepted Answer

A material with low resistivity.

Question 18

A graph of current $$I$$ versus potential difference $$\Delta V$$ for a wire is a straight line through the origin. What does the slope of this line represent?

Accepted Answer

The inverse of the resistance $$1/R.$$

Question 19

In a real-world scenario, why do electrical wires heat up when a current flows through them?

Accepted Answer

Because collisions between electrons and atoms convert electrical energy into thermal energy.

Currents, Resistance, and Ohm’s Law: Study Notes for Physics with Calculus

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