Question 1

Which of the following best describes the function of a capacitor in a DC circuit?

Accepted Answer

It stores electrical energy in the form of an electric field.

Question 2

Given two capacitors, $$C_1 = 2$$\ \mu F$$ and C_2$ = 4\ \mu F$$, connected in series, what is their equivalent capacitance?

Accepted Answer

$$C_{eq} = 2.67\ \mu F$$

Question 3

A battery of emf $$\mathcal{E}$$ and internal resistance $$r is $$connected to a resistor $$R. $$What is the terminal voltage $$V$$ across the battery?

Accepted Answer

$$V = \mathcal{E} - Ir$$

Question 4

Which of the following statements about the charging of a capacitor in an RC circuit is correct?

Accepted Answer

The voltage across the capacitor approaches the battery voltage asymptotically.

Question 5

If three capacitors $$C_1$$, $$C_2$$, and $$C_3$$ are connected in parallel, what is the total capacitance?

Accepted Answer

$$C_{eq} = C_1$ + C_2$ + C_3$

Question 6

A circuit contains a battery, a resistor, and a capacitor in series. If the time constant is $$	au = RC$$, what happens to the time constant if the resistance is doubled?

Accepted Answer

The time constant is doubled.

Question 7

Which equation correctly gives the charge $$q(t) on a $$capacitor at time $$t$$ during charging in an RC circuit?

Accepted Answer

$$q(t) = Q_{max} (1 - e$$^{-t/RC}$$)$$

Question 8

In a circuit, the sum of the potential differences around any closed loop must be zero. This is an application of which law?

Accepted Answer

Kirchhoff's Voltage Law

Question 9

A parallel plate capacitor has plates of area $$A$$ and separation $$d. If a $$dielectric of constant $$\kappa is $$inserted, what is the new capacitance?

Accepted Answer

$$C = \kappa \frac{\$$varepsilon_0$$ A}{d}$$

Question 10

Which of the following will increase the capacitance of a parallel plate capacitor?

Accepted Answer

Inserting a dielectric material between the plates

Question 11

A battery with emf $$\mathcal{E}$$ and internal resistance $$r is $$connected to a load resistor $$R. If$$ $$R \gg r$$, what is the approximate terminal voltage?

Accepted Answer

$$V \approx \mathcal{E}$$

Question 12

If a circuit contains three resistors $$R_1$$, $$R_2$$, and $$R_3 in $$series, what is the total resistance?

Accepted Answer

$$R_{eq} = R_1$ + R_2$ + R_3$

Question 13

A capacitor is connected to a battery and fully charged. If the battery is then removed and the plates are separated further, what happens to the voltage across the capacitor?

Accepted Answer

The voltage increases.

Question 14

Which of the following is NOT a correct statement about the behavior of current in a simple RC circuit during charging?

Accepted Answer

The current increases as the capacitor charges.

Question 15

In a multi-loop circuit, which rule is used to determine the current at a junction?

Accepted Answer

Kirchhoff's Current Law

Question 16

A capacitor is made of two plates of area $$A$$ separated by distance $$d. If $$the area is doubled and the distance is halved, how does the capacitance change?

Accepted Answer

It is quadrupled.

Question 17

Which of the following is the correct expression for the energy stored in a capacitor?

Accepted Answer

$$U = \frac{1}{2}CV^2$

Question 18

A circuit contains a battery, a resistor, and a capacitor in series. If the battery is replaced with one of higher emf, what happens to the final charge on the capacitor?

Accepted Answer

It increases.

Question 19

If a dielectric is inserted between the plates of a charged, isolated capacitor, what happens to the electric field between the plates?

Accepted Answer

It decreases.

Question 20

A student connects two capacitors $$C_1$$ and $$C_2 in $$parallel and then in series. Which configuration gives the higher total capacitance?

Accepted Answer

Parallel configuration

Electric Circuits: Capacitors, Batteries, and Kirchhoff's Rules

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