Question 1

Which equation correctly expresses Ohm's Law for the circuit shown in the first image (a single resistor $$R$$ with current $$I$$ flowing from $$A to$$ $$B$$)?

Accepted Answer

$$I = \frac{\Delta V_{AB}}{R}$$

Question 2

A circuit contains three resistors in series: $$R_1 = 2$$\,\Omega$$, R_2$ = 3\,\Omega$$, and $$R_3 = 5$$\,\Omega$$. What is the equivalent resistance R$$_{eq}$$?

Accepted Answer

$$R_{eq} = 10\,\Omega$$

Question 3

Which of the following best describes the function of a fuse in a household electrical circuit?

Accepted Answer

It melts and opens the circuit if the current becomes too large, preventing overheating and potential fires.

Question 4

Given two resistors $$R_1$$ and $$R_2 in $$parallel, which equation gives the equivalent resistance $$R_{eq}$$?

Accepted Answer

$$\frac{1}{R_{eq}} = \frac{1}{R_1$} + \frac{1}{R_2$}$$

Question 5

A lamp, toaster, and TV are connected in parallel to a fuse as shown. If the toaster develops a short circuit, what is the most likely outcome?

Accepted Answer

The fuse will blow, cutting off power to all devices.

Question 6

Which of the following is a correct statement about the current at a node according to Kirchhoff's Current Law?

Accepted Answer

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

Question 7

A 9V battery with internal resistance $$r = 1\,\Omega is $$short-circuited with a wire. What is the current through the wire?

Accepted Answer

$$I = 9\,A$$

Question 8

Which equation gives the power dissipated in a resistor $$R$$ with current $$I$$ flowing through it?

Accepted Answer

$$P = I^2$ R$$

Question 9

If a voltmeter is connected across a resistor, what property should the voltmeter have to minimize its effect on the circuit?

Accepted Answer

Very large internal resistance

Question 10

A battery with emf $$V$$ and internal resistance $$r is $$connected to a load resistor $$R_L. $$What is the voltage across the load?

Accepted Answer

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

Question 11

Which of the following is a real-world cause for a blown fuse in a household circuit?

Accepted Answer

Too many devices plugged into one circuit

Question 12

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

Accepted Answer

$$P = 0.113\,W$$

Question 13

Which of the following statements about ammeters is correct?

Accepted Answer

An ammeter must have very small internal resistance and is connected in series.

Question 14

If three resistors $$R_1 = 2$$\,\Omega$$, R_2$ = 3\,\Omega$$, and $$R_3 = 6$$\,\Omega$$ are connected in parallel, what is the equivalent resistance?

Accepted Answer

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

Question 15

A $$1.5\,V$$ battery is connected to a $$5\,\Omega$$ resistor. What is the current through the resistor?

Accepted Answer

$$I = 0.3\,A$$

Question 16

Which of the following is a correct application of Kirchhoff’s Loop Rule?

Accepted Answer

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

Question 17

If a wire is damaged and its insulation is broken, which electrical hazard is most likely to occur?

Accepted Answer

Short circuit

Question 18

Which of the following is NOT a type of resistor shown in the resistor image?

Accepted Answer

Capacitor

Question 19

A voltmeter is connected across a $$10\,\Omega$$ resistor in a circuit. If the voltmeter has a very low internal resistance, what is the likely effect?

Accepted Answer

It will draw significant current and affect the measurement.

Question 20

Which of the following best explains why a real battery's voltage across the load decreases as more current is drawn?

Accepted Answer

The internal resistance causes a voltage drop inside the battery.

Study Notes: Ohm’s Law, Resistors, and DC Circuits

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