Electrostatics
Beginner
Electric Charge
Source: High school physics (Chinese)
Problem
There are four charged objects: A, B, C, and D. Object A repels object B, A attracts C, and C repels D. Object D is known to have a positive charge.
What is the sign of the charge on object B?
Negative
We can deduce the charges step-by-step using the principle that like charges repel and opposite charges attract.
- C repels D (+ charge) $\implies$ C has a positive (+) charge.
- A attracts C (+ charge) $\implies$ A has a negative (-) charge.
- A repels B (- charge) $\implies$ B has a negative (-) charge.