Question Detail
Question
How much work is required to carry an electron from the positive terminal of a 12-V battery to the negative terminal? (Given: elementary charge e = 1.6 × 10-19 C)
Correct Answer
Option A is the correct answer.
Detailed Explanation
This is Solved Problem 25.2 on page 16. The charge of an electron is q = -e = -1.6 × 10-19 C. Moving from the positive to the negative terminal means the potential difference is a drop, so V = -12 V. The work done is W = qV = (-1.6 × 10-19 C) * (-12 V) = 1.92 × 10-18 J. The document rounds this to 1.9 × 10-18 J. Positive work means energy must be supplied to move the electron against its natural tendency.
Hint
Consider the sign of the electron's charge and the potential drop when moving from the positive to the negative terminal of a battery. Work = charge × potential difference.