Use electrical energy formula E = V I t to find voltage

Steps:

• Calculate total charge transferred: Q = I × t = 2.0 A × 5.0 s = 10 C
• Use energy formula: E = V Q, so V = E / Q = 20 J / 10 C = 2.0 V

Why B is correct:

• Matches V = E / (I t) from the definition of electrical work, where energy transferred equals voltage times charge.

Why the others are wrong:

• A: 0.5 V from incorrectly using E / (I × 2t) = 20 / 20 = 1, halved erroneously.
• C: 8 V from swapping time and current in denominator: 20 / (5 / 2) = 8.
• D: 5 V from using E / I only: 20 / (2 × 2), ignoring time.

Final answer: B