Calculate the electric field intensity which would be just sufficient to balance the weight of a particle of charge `-10 muC` and mass 10 mg. `("Take "g=10 ms^(2))`

Explanation

As force on a charge q in an electric field `vec(E)` is
`vec(F)_(q) = qvec(E)`
So according to given problem

`|vec(F)_(q)| = |vec(W)|` i.e., `|q|E = mg`
i.e., `E = (mg)/(|q|) = 10 N//C`., in downward direction.