Question

Flux coming out from a balloon of radius 10 cm is 1.0*10^3 N.m^2.C-1^-1. If the radius of the balloon is doubled, the flux coming out from the balloon will be _______

(a) 0.5 times

(b) 2 times

(c) Same

(d) 4 times

The question was posed to me during an internship interview.

This interesting question is from Electric Flux in division Charges and Fields of Physics – Class 12

Answer 1

Right option is (c) Same

For explanation I would say: If the radius of the balloon is 2 times the initial value, the surface area of the balloon will be 4 times the initial value because of surface area=4π(radius)^2. But in this case, flux coming out from the balloon is dependent only upon the charge inside the balloon, not on the area of the surface. As charge enclosed in the balloon is the same in both the cases, the flux will also be the same.