Question Detail

PHY 102 ELECTROSTATICS Objective Question

Question

The document states that the Electric Potential Energy (EPE) for moving a 2µC charge from 2 mm to 5 mm in the field of a 3µC charge is -1.62 J. What does the negative sign of this work imply in this context?
Options
A Work was done by the field, as the charge 'willingly' moved.
Correct Answer
B Work was done against the field, requiring external effort.
C The charges repelled each other, increasing potential energy.
D The kinetic energy of the charge decreased.
Correct Answer

Option A is the correct answer.

Detailed Explanation

The example explanation states, 'Notice that the work done by us is negative. This is because the charge 'willingly' goes. It is like when descending a staircase or walking downhill. The work you do is negative while the work done by gravity is positive. In this case, the work done by the field is positive. The field actually pushes the charge away.' (page 16).

Hint

A negative work done *by us* means the field is doing positive work, indicating the charge moves 'willingly' due to the field's force.

Question Info