An oil drop, carrying six electronic charges and having a mass of 1.6 x 10-12g, falls with some terminal velocity….

Q.An oil drop, carrying six electronic charges and having a mass of 1.6×10^-12g, falls with some terminal velocity in a medium. What magnitude of vertical electric field is required to make the drop move upward with the same speed as it was formerly moving downward with? Ignore buoyancy.

(a) 10⁵ NC^-1

(b) 10⁴ NC^-1

(c) 3.3 × 10⁴ NC^-1

(d) 3.3 × 10⁵ NC^-1

Ans: (c)