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

$$V_{AB} = IR$$

Question 2

A circuit contains four resistors in series as shown in the fourth image. If $$R_1 = 2$$\,\Omega$$, R_2$ = 3\,\Omega$$, $$R_3 = 5$$\,\Omega$$, and R_4$ = 10\,\Omega$$, what is the equivalent resistance $$R_{equiv}$$?

Accepted Answer

$$R_{equiv} = 20\,\Omega$$

Question 3

Which of the following best describes the function of a fuse in a household circuit, as shown in the sixth image?

Accepted Answer

It melts and opens the circuit if the current is too high.

Question 4

Given the parallel resistor circuit in the fifth image, which equation gives the equivalent resistance $$R_{equiv}$$?

Accepted Answer

$$\frac{1}{R_{equiv}} = \frac{1}{R_1$} + \frac{1}{R_2$} + \frac{1}{R_3$} + \frac{1}{R_4$}$$

Question 5

If a lamp, toaster, and TV are connected in parallel to a main line as shown in the sixth image, what happens if the toaster is unplugged?

Accepted Answer

The lamp and TV will remain on.

Question 6

Which type of resistor is specifically designed to change resistance with temperature, as shown in the third image?

Accepted Answer

Thermistor

Question 7

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

Accepted Answer

$$I = 9\,A$$

Question 8

In the circuit with a real battery (internal resistance $$r) $$and a load resistor $$R_L$$, which equation gives the voltage across the load $$V_L$$?

Accepted Answer

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

Question 9

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 10

A digital multimeter (shown in the image) is used to measure current in a circuit. How should it be connected?

Accepted Answer

In series with the component

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 lamp rated at 60W is connected to a 120V supply. What is the resistance of the lamp?

Accepted Answer

$$R = 240\,\Omega$$

Question 13

Which of the following is a consequence of a short circuit in a household wiring system?

Accepted Answer

The current increases dramatically, possibly blowing a fuse.

Question 14

If a voltmeter is connected across a resistor, what should its internal resistance be to minimize measurement error?

Accepted Answer

Very large

Question 15

Which equation correctly gives the power dissipated in a resistor using Ohm's Law?

Accepted Answer

$$P = I^2$ R$$

Question 16

A circuit contains a 12V battery and two resistors in series: $$R_1 = 2$$\,\Omega$$ and R_2$ = 4\,\Omega. $$What is the current in the circuit?

Accepted Answer

$$I = 2\,A$$

Question 17

Which of the following is NOT a reason why a household circuit might draw too much current?

Accepted Answer

High resistance in the wires

Question 18

If a resistor is dissipating 0.5W of power and the current through it is 0.1A, what is the voltage across the resistor?

Accepted Answer

$$V = 5\,V$$

Question 19

Which of the following statements about ammeters is correct?

Accepted Answer

They are connected in series and have low internal resistance.

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

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