Questions: Ohm's Law: V = IR

Question 1

A 12 V battery is connected to a 4 Ω resistor. What current flows?

• A. 48 A
• B. 3 A
• C. 0.33 A
• D. 16 A

Answer: (B)

Using Ohm's Law: I = V/R = 12/4 = 3 A.

Question 2

If the resistance in a circuit doubles while the voltage stays the same, the current is cut in half.

• T. True
• F. False

Answer: True

From I = V/R, if R doubles and V stays constant, I becomes V/(2R) = half the original current.

Question 3

A current of 2 A flows through a 10 Ω resistor. What is the voltage across it?

Model answer: 20 V, because V = IR = 2 × 10 = 20 V.

Applying Ohm's Law directly: voltage = current × resistance = 2 A × 10 Ω = 20 V.