Q: Given a 24 V battery and a total circuit resistance of 240 Ω, what is the total current supplied by the battery?

$$I = \frac{24\text{ V}}{240 \Omega} = 0.10 \text{ A}$$

Q: What is the voltage between points A and B in the circuit if the current through the equivalent resistance between A and B is 0.10 A and the resistance is 130 Ω?

$$V_{AB} = 0.10 \text{ A} \times 130 \Omega = 13 \text{ V}$$

Q: A car battery has an emf of 12.0 V and an internal resistance of 0.010 Ω. What is the terminal voltage when the current drawn is 100.0 A?

$$V = 12.0 \text{ V} - (100.0 \text{ A} \times 0.010 \Omega) = 11.0 \text{ V}$$

Q: In a circuit with a 12 V battery, a 5 Ω resistor, and a 1 Ω resistor in series, what is the current through the circuit?

$$I = \frac{12 \text{ V}}{5 \Omega + 1 \Omega} = 2 \text{ A}$$

Q: A circuit contains a 24 V battery, a 12 Ω resistor, a 6 V battery, and an 8 Ω resistor. Using Kirchhoff’s loop rule, what is the equation for the loop?

$$24 \text{ V} - I \times 12 \Omega - 6 \text{ V} - I \times 8 \Omega = 0$$

Q: A circuit contains a battery (emf 12 V, internal resistance 0.010 Ω) and a load resistor. If the current is 10 A, what is the power delivered to the load?

$$P = V_{\text{terminal}} \times I = (12.0 \text{ V} - 0.10 \text{ V}) \times 10 \text{ A} = 119 \text{ W}$$

Question 1

In the circuit shown, what is the equivalent resistance of the 220 Ω and 250 Ω resistors when they are connected in parallel?

Accepted Answer

$$R = \frac{1}{\frac{1}{220 \Omega} + \frac{1}{250 \Omega}} = 117.6 \Omega$$

Question 2

Given a 24 V battery and a total circuit resistance of 240 Ω, what is the total current supplied by the battery?

Accepted Answer

$$I = \frac{24	ext{ V}}{240 \Omega} = 0.10 	ext{ A}$$

Question 3

What is the voltage between points A and B in the circuit if the current through the equivalent resistance between A and B is 0.10 A and the resistance is 130 Ω?

Accepted Answer

$$V_{AB} = 0.10 	ext{ A} 	imes 130 \Omega = 13 	ext{ V}$$

Question 4

A car battery has an emf of 12.0 V and an internal resistance of 0.010 Ω. What is the terminal voltage when the current drawn is 100.0 A?

Accepted Answer

$$V = 12.0 	ext{ V} - (100.0 	ext{ A} 	imes 0.010 \Omega) = 11.0 	ext{ V}$$

Question 5

Why do car headlights dim when the starter motor is turned on?

Accepted Answer

The increased current causes a larger voltage drop across the battery's internal resistance, reducing the terminal voltage.

Question 6

Which equation correctly represents the junction rule in a circuit?

Accepted Answer

$$I_{	ext{tot}} = I_1$ + I_2$

Question 7

Which statement best describes Kirchhoff’s loop rule?

Accepted Answer

The sum of all potential changes around a closed loop is zero.

Question 8

In a circuit with a 12 V battery, a 5 Ω resistor, and a 1 Ω resistor in series, what is the current through the circuit?

Accepted Answer

$$I = \frac{12 	ext{ V}}{5 \Omega + 1 \Omega} = 2 	ext{ A}$$

Question 9

A circuit contains a 24 V battery, a 12 Ω resistor, a 6 V battery, and an 8 Ω resistor. Using Kirchhoff’s loop rule, what is the equation for the loop?

Accepted Answer

$$24 	ext{ V} - I 	imes 12 \Omega - 6 	ext{ V} - I 	imes 8 \Omega = 0$$

Question 10

In a circuit with a battery of emf $$\mathcal{E}$$ and internal resistance $$r$$, what is the terminal voltage when a current $$I is $$drawn?

Accepted Answer

$$V = \mathcal{E} - Ir$$

Question 11

A circuit contains a battery (emf 12 V, internal resistance 0.010 Ω) and a load resistor. If the current is 10 A, what is the power delivered to the load?

Accepted Answer

$$P = V_{	ext{terminal}} 	imes I = (12.0 	ext{ V} - 0.10 	ext{ V}) 	imes 10 	ext{ A} = 119 	ext{ W}$$

Question 12

In the circuit with a battery, alternator, and headlights, which equation represents the junction rule at point B?

Accepted Answer

$$I_A + I_B = I_H$$

Question 13

If a battery has an emf of 12 V and internal resistance of 0.010 Ω, what is the terminal voltage when the current is 0 A?

Accepted Answer

$$V = 12 	ext{ V}$$

Question 14

Which reasoning strategy is NOT recommended when applying Kirchhoff’s rules?

Accepted Answer

Ignoring the direction of current in each branch.

Question 15

A circuit has resistors of 110 Ω, 180 Ω, 220 Ω, and 250 Ω. Which combination gives the smallest equivalent resistance?

Accepted Answer

220 Ω and 250 Ω in parallel

Question 16

In a circuit, if the current through a resistor is negative after solving, what does this indicate?

Accepted Answer

The actual direction of current is opposite to the assumed direction.

Question 17

If the power delivered to headlights is $$P = \frac{V_{AB}^2}{R}$$, what happens to the power when $$V_{AB}$$ decreases due to increased current draw?

Accepted Answer

The power decreases because $$P is $$proportional to $$V_{AB}^2.$$

Question 18

Which of the following is a correct application of Kirchhoff’s loop rule in a circuit with two batteries and two resistors?

Accepted Answer

$$	ext{emf}_1 - I R_1$ - 	ext{emf}_2 - I R_2$ = 0$$

Lec 8

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