Physics · Oct / Nov 2021 · Paper 12 · Question 31

A positively charged plastic rod is held near but not touching an insulated and previously uncharged metal ball. No charge leaves the rod. [diagram: plastic rod with positive charges, metal ball labelled left and right] What are possible charges on the left-hand side and right-hand side of the ball?

1. Acharge on left-hand side of ball: –2.0 × 10–9 A; charge on right-hand side of ball: –1.0 × 10–9 A
2. Bcharge on left-hand side of ball: –2.0 × 10–9 A; charge on right-hand side of ball: +2.0 × 10–9 A
3. Ccharge on left-hand side of ball: –2.0 × 10–9 C; charge on right-hand side of ball: +2.0 × 10–9 C
4. Dcharge on left-hand side of ball: +2.0 × 10–9 C; charge on right-hand side of ball: –2.0 × 10–9 C

As printed in the paper