Question

Suppose we have large number of identical particles, very small in size. Any of them at `10 cm` separation repel with a force of `3xx10^(-10) N`. If one of them is at `10 cm` from a group of `n` others, how strongly do you expect it to be repelled?
A. `3xx10^(-10) N`
B. `3nxx10^(-10)N`
C. `(3xx10^(-10))/(n)N`
D. Can not be calculated

Answer 1

Correct Answer - b
The group of `n` small charged particles must behaves as a single point charge, so that if can have a separation of `10 cm` from the one particle in question. Obviously force on this particle due to the group of `n` particles is `n` times he force due a single particle. Hence, force dut to group of `n` particles,
`F= nxx3xx10^(-10)N`