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Ohm's Law worksheet

Grades 8–9 · CCSS HSA.CED.A.4

Solve each problem and show your work. Round answers to 2 decimal places where needed.

1.
Problem 1.
- Values you know: Current and resistance
- Current (I): 2 A
- Resistance (R): 6 Ω
Find: Voltage
Answer
2.
Problem 2.
- Values you know: Resistance and power
- Resistance (R): 5 Ω
- Power (P): 19 W
Find: Voltage
Answer
3.
Problem 3.
- Values you know: Voltage and power
- Voltage (V): 11 V
- Power (P): 28 W
Find: Current
Answer
4.
Problem 4.
- Values you know: Voltage and resistance
- Voltage (V): 14 V
- Resistance (R): 7 Ω
Find: Current
Answer
5.
Problem 5.
- Values you know: Voltage and resistance
- Voltage (V): 11 V
- Resistance (R): 5 Ω
Find: Current
Answer
6.
Problem 6.
- Values you know: Voltage and current
- Voltage (V): 10 V
- Current (I): 3 A
Find: Resistance
Answer
7.
Problem 7.
- Values you know: Voltage and resistance
- Voltage (V): 18 V
- Resistance (R): 9 Ω
Find: Current
Answer
8.
Problem 8.
- Values you know: Voltage and current
- Voltage (V): 15 V
- Current (I): 2 A
Find: Resistance
Answer
9.
Problem 9.
- Values you know: Resistance and power
- Resistance (R): 6 Ω
- Power (P): 18 W
Find: Voltage
Answer
10.
Problem 10.
- Values you know: Current and resistance
- Current (I): 2 A
- Resistance (R): 4 Ω
Find: Voltage
Answer

Answer key: Ohm's Law worksheet

1. Voltage: 12 V
1. Find the voltage with Ohm's law: multiply the current by the resistance
  $V$ $= 2 \times 6$ $= 12 V$
2. Find the power: square the current (multiply it by itself), then multiply by the resistance
  $P$ $= 2^{2} \times 6$ $= 24 W$
2. Voltage: 9.75 V
1. Find the voltage: multiply the power by the resistance, then take the square root
  $V$ $= \sqrt{19 \times 5}$ $= 9.7467943448 V$
2. Find the current: divide the power by the resistance, then take the square root
  $I$ $= \sqrt{\frac{19}{5}}$ $= 1.949358869 A$
3. Current: 2.55 A
1. Find the current: divide the power by the voltage, since power is voltage times current
  $I$ $= \frac{28}{11}$ $= 2.5454545455 A$
2. Find the resistance: square the voltage, then divide by the power
  $R$ $= \frac{11^{2}}{28}$ $= 4.3214285714 Ω$
4. Current: 2 A
1. Find the current with Ohm's law: divide the voltage by the resistance
  $I$ $= \frac{14}{7}$ $= 2 A$
2. Find the power: square the voltage (multiply it by itself), then divide by the resistance
  $P$ $= \frac{14^{2}}{7}$ $= 28 W$
5. Current: 2.2 A
1. Find the current with Ohm's law: divide the voltage by the resistance
  $I$ $= \frac{11}{5}$ $= 2.2 A$
2. Find the power: square the voltage (multiply it by itself), then divide by the resistance
  $P$ $= \frac{11^{2}}{5}$ $= 24.2 W$
6. Resistance: 3.33 Ω
1. Find the resistance with Ohm's law: divide the voltage by the current
  $R$ $= \frac{10}{3}$ $= 3.3333333333 Ω$
2. Find the power: multiply the voltage by the current
  $P$ $= 10 \times 3$ $= 30 W$
7. Current: 2 A
1. Find the current with Ohm's law: divide the voltage by the resistance
  $I$ $= \frac{18}{9}$ $= 2 A$
2. Find the power: square the voltage (multiply it by itself), then divide by the resistance
  $P$ $= \frac{18^{2}}{9}$ $= 36 W$
8. Resistance: 7.5 Ω
1. Find the resistance with Ohm's law: divide the voltage by the current
  $R$ $= \frac{15}{2}$ $= 7.5 Ω$
2. Find the power: multiply the voltage by the current
  $P$ $= 15 \times 2$ $= 30 W$
9. Voltage: 10.39 V
1. Find the voltage: multiply the power by the resistance, then take the square root
  $V$ $= \sqrt{18 \times 6}$ $= 10.3923048454 V$
2. Find the current: divide the power by the resistance, then take the square root
  $I$ $= \sqrt{\frac{18}{6}}$ $= 1.7320508076 A$
10. Voltage: 8 V
1. Find the voltage with Ohm's law: multiply the current by the resistance
  $V$ $= 2 \times 4$ $= 8 V$
2. Find the power: square the current (multiply it by itself), then multiply by the resistance
  $P$ $= 2^{2} \times 4$ $= 16 W$