Q: A $$9.0\,\mathrm{V}$$ battery supplies $$0.36\,\mathrm{A} to a $$resistor. What is the power dissipated in the resistor?

$$P = 9.0 \times 0.36 = 3.24\,\mathrm{W}$$

Q: In a circuit, the current through a $$25\,\Omega$$ resistor is $$0.11\,\mathrm{A}. $$What is the voltage drop across the resistor?

$$\Delta V = 0.11 \times 25 = 2.75\,\mathrm{V}$$

Question 1

A real battery is modeled as an ideal voltage source $$V in $$series with an internal resistance $$r. If a $$load resistor $$R_L is $$connected across the battery, what is the voltage $$V_L$$ across the load resistor?

Accepted Answer

$$V_L = V \frac{R_L}{R_L + r}$$

Question 2

In the circuit shown, a battery with emf $$\mathcal{E}$$ and internal resistance $$r is $$connected to a resistor $$R. $$What is the current $$I in $$the circuit?

Accepted Answer

$$I = \frac{\mathcal{E}}{R + r}$$

Question 3

A voltmeter is used to measure the voltage across a resistor in a circuit. How should the voltmeter be connected?

Accepted Answer

In parallel with the resistor

Question 4

A $$1.5\,\mathrm{V}$$ battery with internal resistance $$0.5\,\Omega is $$connected to a $$4.5\,\Omega$$ load. What is the current through the load?

Accepted Answer

$$I = \frac{1.5}{4.5 + 0.5} = 0.3\,\mathrm{A}$$

Question 5

Which of the following best describes why a real battery 'dies' over time, even though the chemical reaction can still produce a potential difference?

Accepted Answer

The internal resistance $$r$$ increases, reducing the voltage available to the load.

Question 6

A $$9.0\,\mathrm{V}$$ battery supplies $$0.36\,\mathrm{A} to a $$resistor. What is the power dissipated in the resistor?

Accepted Answer

$$P = 9.0 	imes 0.36 = 3.24\,\mathrm{W}$$

Question 7

In a circuit, the current through a $$25\,\Omega$$ resistor is $$0.11\,\mathrm{A}. $$What is the voltage drop across the resistor?

Accepted Answer

$$\Delta V = 0.11 	imes 25 = 2.75\,\mathrm{V}$$

Question 8

Which equation correctly expresses the voltage at point $$b$$ relative to $$a$$ for a resistor $$R$$ with current $$I$$ flowing from $$a to$$ $$b$$?

Accepted Answer

$$V_b = V_a - IR$$

Question 9

A $$1.5\,\mathrm{V}$$ battery is connected to a $$20\,\Omega$$ resistor. What is the power dissipated in the resistor?

Accepted Answer

$$P = \frac{(1.5)^2$}{20} = 0.113\,\mathrm{W}$$

Question 10

If a battery is connected backward while charging another battery, what is a likely consequence?

Accepted Answer

A large amount of gas will be produced and huge power will be dissipated in the wires.

Question 11

In a circuit with two batteries of emf $$\mathcal{E}_1$$ and $$\mathcal{E}_2$$ and internal resistances $$r_1$$ and $$r_2$$ connected in series with a resistor $$R$$, what is the total current $$I if $$both batteries are oriented in the same direction?

Accepted Answer

$$I = \frac{\mathcal{E}_1 + \mathcal{E}_2}{R + r_1$ + r_2$}$$

Question 12

A digital multimeter is set to measure voltage. Which configuration is correct for measuring the voltage across a resistor in a circuit?

Accepted Answer

Connect the probes in parallel with the resistor.

Question 13

In the circuit shown, if the current through a $$50\,\Omega$$ resistor is $$0.11\,\mathrm{A}$$, what is the voltage drop across it?

Accepted Answer

$$\Delta V = 0.11 	imes 50 = 5.5\,\mathrm{V}$$

Question 14

Which of the following statements about ideal and real batteries is correct?

Accepted Answer

An ideal battery has zero internal resistance.

Question 15

If a resistor $$R is $$connected to an ideal battery of voltage $$V$$, what is the current through the resistor?

Accepted Answer

$$I = \frac{V}{R}$$

DC Circuits: Batteries, Resistors, and Circuit Analysis

Study Guide - Practice Questions

Study Guide - Flashcards