1 n
The force attracting electrical charged objects follows the inverse square law. So we calculate how much further apart the objects are by dividing the new distance by the original distance, giving
4 m / 2 m = 2
So the new distance is twice as far as the original distance. That means that the attractive force will be the inverse square, giving
1/(2^2) = 1/4 = 0.25
So the attractive force will be one fourth as strong. The original force was 4 n, so the new force will be 4/4 n = 1 n
