Q: Which of the following is a correct application of Kirchhoff's loop rule?

$$\Delta V_1$ + \Delta V_2$ + \Delta V_3$ = 0$$ \text{ around any closed loop}

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 breaks the circuit if the current exceeds a safe value.

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 main line with a fuse. 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

If 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 7

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

Accepted Answer

$$I = 9\,A$$

Question 8

Which of the following is a correct application of Kirchhoff's loop rule?

Accepted Answer

$$\Delta V_1$ + \Delta V_2$ + \Delta V_3$ = 0$$ 	ext{ around any closed loop}

Question 9

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 10

Which of the following statements about ammeters and voltmeters is correct?

Accepted Answer

Ammeters are connected in series and should have very low internal resistance.

Question 11

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 12

A household circuit is protected by a $$10\,A$$ fuse. If three $$1500\,W$$ appliances are plugged in simultaneously to a $$120\,V$$ supply, what will happen?

Accepted Answer

The fuse will blow because the total current exceeds $$10\,A.$$

Question 13

Which of the following is a correct expression for the power dissipated in a resistor using Ohm's law?

Accepted Answer

$$P = I^2$ R$$

Question 14

If a voltmeter with low internal resistance is used to measure the voltage across a resistor, what is the likely effect?

Accepted Answer

It will draw significant current and give an inaccurate reading.

Question 15

A wire is damaged and its insulation is broken, exposing the conductor. What electrical hazard does this present?

Accepted Answer

It can cause a ground fault, creating a dangerous path for current.

Question 16

Which of the following is NOT a plausible reason for a circuit breaker to trip?

Accepted Answer

A resistor with very high resistance is added to the circuit.

Question 17

In a series circuit with a battery and two resistors $$R_1$$ and $$R_2$$, what is the current $$I if $$the battery voltage is $$V$$?

Accepted Answer

$$I = \frac{V}{R_1$ + R_2$}$$

Question 18

A digital multimeter is used to measure current in a circuit. How should it be connected?

Accepted Answer

In series with the component whose current is to be measured.

Question 19

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.

Ohm’s Law, Resistors, and DC Circuits: Series and Parallel Connections

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