Q: A 12 V battery with an internal resistance of $$1\ \Omega is $$connected to a $$5\ \Omega$$ resistor. What is the terminal voltage across the battery when the circuit is closed?

$$V_{terminal} = 10\ \text{V}$$

Question 1

Which circuit component is represented by the symbol consisting of two parallel lines, and what is its primary function in a circuit?

Accepted Answer

A capacitor; it stores electrical energy in an electric field.

Question 2

Given three resistors with values $$R_1 = 2$$\ \Omega$$, R_2$ = 3\ \Omega$$, and $$R_3 = 6$$\ \Omega$$ connected in parallel, what is the equivalent resistance R$$_{eq}$$?

Accepted Answer

$$R_{eq} = 1\ \Omega$$

Question 3

A 12 V battery with an internal resistance of $$1\ \Omega is $$connected to a $$5\ \Omega$$ resistor. What is the terminal voltage across the battery when the circuit is closed?

Accepted Answer

$$V_{terminal} = 10\ 	ext{V}$$

Question 4

Which of the following best describes the function of an ammeter and how it should be connected in a circuit?

Accepted Answer

It measures current and is connected in series.

Question 5

Two identical light bulbs are connected to a 24 V battery, first in series and then in parallel. In which configuration will the bulbs be brighter and why?

Accepted Answer

Parallel, because each bulb receives the full voltage.

Question 6

A 1250 W heater is designed to operate at 115 V. What is the resistance of the heating coil?

Accepted Answer

$$R = 10.6\ \Omega$$

Question 7

Which equation correctly expresses the power dissipated in a resistor in terms of current $$I$$ and resistance $$R$$?

Accepted Answer

$$P = I^2$R$$

Question 8

In a series RC circuit, the time constant $$	au is $$given by which of the following expressions?

Accepted Answer

$$	au = RC$$

Question 9

A capacitor is charged through a resistor $$R by a $$battery of emf $$\varepsilon. $$What is the charge on the capacitor at time $$t = RC$$?

Accepted Answer

$$q = C\varepsilon (1 - e$$^{-1}$$)$$

Question 10

Which of the following statements about Kirchhoff’s loop rule is correct?

Accepted Answer

The sum of the potential differences around any closed loop is zero.

Question 11

A real battery is modeled as an ideal emf $$\varepsilon in $$series with an internal resistance $$r. If a $$current $$I$$ flows, what is the terminal voltage $$V_{ab}$$?

Accepted Answer

$$V_{ab} = \varepsilon - Ir$$

Question 12

A voltmeter is used to measure the voltage across a resistor in a circuit. To minimize measurement error, the voltmeter should have:

Accepted Answer

Very high resistance

Question 13

In a discharging RC circuit, what is the expression for the charge on the capacitor as a function of time?

Accepted Answer

$$q(t) = Q_0$ e$$^{-t/RC}$$

Question 14

A 9 V battery with an internal resistance of $$2\ \Omega is $$connected to a $$4\ \Omega$$ resistor. What is the current in the circuit?

Accepted Answer

$$I = 1.5\ 	ext{A}$$

Question 15

Which of the following is NOT a correct rule for applying Kirchhoff’s loop rule?

Accepted Answer

The sum of the voltage changes around a closed loop is equal to the emf of the battery.

Question 16

A galvanometer is used to design an ammeter. Why is a shunt resistor used in parallel with the galvanometer?

Accepted Answer

To allow the ammeter to measure larger currents without damaging the galvanometer.

Question 17

If a $$10\ \Omega$$ resistor and a $$20\ \Omega$$ resistor are connected in series to a $$30\ 	ext{V}$$ battery, what is the current through the circuit?

Accepted Answer

$$I = 1\ 	ext{A}$$

Question 18

Which of the following best describes the effect of adding more resistors in parallel to a circuit?

Accepted Answer

The total resistance decreases.

Question 19

A $$6\ \mu F$$ capacitor is charged to $$12\ 	ext{V}$$ and then disconnected from the battery. It is then connected across a $$3\ \Omega$$ resistor. What is the initial current through the resistor?

Accepted Answer

$$I_0 = 0.024$$\ 	ext{A}$$

Fundamentals of Electric Circuits: Series, Parallel, Power, Kirchhoff’s Rules, and RC Circuits

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