AP Physics 2 Quiz: Electric Power

What this quiz covers

This quiz focuses on Electric Power, giving you a quick way to practice the rules, question types, and explanations that matter most for AP Physics 2.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. smaller, because $P=IV$ and $I$ is smaller while $V$ is constant (correct answer)
2. larger, because the device has been on longer and used more energy
3. unchanged, because the voltage source is constant
4. larger, because a smaller current implies a larger resistance and thus larger power

Question 2

1. twice as large, because doubling voltage doubles power
2. four times as large, because $P=\dfrac{V^2}{R}$ and $R$ is constant (correct answer)
3. unchanged, because resistance is unchanged
4. half as large, because higher voltage reduces current draw

Question 3

1. half as large, because its resistance is half
2. twice as large, because $P=\dfrac{V^2}{R}$ at the same voltage (correct answer)
3. the same, because both are connected to the same battery
4. four times as large, because its current is twice and power scales as $I^2$

Question 4

1. unchanged because the battery voltage is fixed
2. twice as large
3. four times as large
4. half as large (correct answer)

Question 5

1. The $10\,\Omega$ resistor, because $P=I^2R$ (correct answer)
2. They dissipate the same power because the time is the same
3. The $5.0\,\Omega$ resistor, because lower resistance means more power
4. They dissipate the same power because both are resistors

Question 6

1. It is $360\ \text{W}$ because power equals energy divided by time
2. It is $24\ \text{W}$ because $P=IV$ and both $I$ and $V$ are constant (correct answer)
3. It is $12\ \text{W}$ because the voltage sets the energy per charge only
4. It is $6\ \text{W}$ because the current is spread over $30\ \text{s}$

Question 7

1. They dissipate the same energy because their currents are different
2. Bulb B dissipates more power because it has the higher current
3. They dissipate the same power because $V_AI_A=V_BI_B$ (correct answer)
4. Bulb A dissipates more power because it has the higher voltage

Question 8

1. It increases because higher resistance always means higher power
2. It stays constant because the battery fixes the power
3. It becomes zero because current must stop immediately
4. It decreases because with constant $V$, $P=\dfrac{V^2}{R}$ (correct answer)

Question 9

1. $R_1$ dissipates more power because it has smaller resistance
2. $R_2$ dissipates more power because it has larger resistance (correct answer)
3. Both dissipate the same power because the current is the same
4. Both dissipate the same power because the total energy is fixed

Question 10

1. $R_2$, because it has the smaller resistance
2. $R_1$, because it has the larger voltage drop at the same current (correct answer)
3. $R_1$ and $R_2$ dissipate equal power because they are in series
4. $R_2$, because it transfers more energy in $10\ \text{s}$

Question 11

1. $R_1$, because lower resistance always means greater power
2. $R_2$, because with equal current $P=I^2R$ is larger for larger $R$ (correct answer)
3. They dissipate equal power because the same current flows through each
4. $R_1$, because it has the smaller voltage drop in series

Question 12

1. doubled
2. unchanged
3. halved
4. quadrupled (correct answer)

Question 13

1. Resistor 1 dissipates three times the power of resistor 2 (correct answer)
2. Resistor 2 dissipates three times the power of resistor 1
3. Both resistors dissipate the same power
4. Both resistors dissipate the same energy but different power

Question 14

1. $R_2$ dissipates more power because it has higher resistance
2. $R_1$ dissipates more power because it draws more current (correct answer)
3. $R_1$ and $R_2$ dissipate equal power because voltage is the same
4. Neither dissipates power because the source is ideal

Question 15

1. greater because the total resistance is greater
2. less because the current is smaller (correct answer)
3. the same because the bulbs are identical
4. zero because the voltage is shared

Question 16

1. Element A, because series elements share voltage equally
2. They dissipate the same power because the current is the same
3. Element B, because $P=IV$ and both have the same $I$ (correct answer)
4. Element A, because lower voltage means higher power

Question 17

1. the same because the current is constant
2. half as large because $P=VI$ and $V$ halves (correct answer)
3. twice as large because the time interval is $10\text{ s}$
4. one-fourth as large because voltage decreased by $6\text{ V}$

Question 18

1. greater, because less current means less energy wasted
2. smaller, because power depends only on time of operation
3. smaller, because with constant $V$ the power $P=IV$ decreases with $I$ (correct answer)
4. unchanged, because constant voltage means constant power

Question 19

1. one-third as large because the voltage increased
2. three times as large because $P=IV$ and $I$ is constant (correct answer)
3. unchanged because the current is constant
4. five times as large because time increases energy

Question 20

1. doubled because the resistance doubled
2. doubled because $P=I^2R$ and $R$ doubled (correct answer)
3. unchanged because the current is the same
4. halved because the current stays constant