1)

Two non conducting solid spheres of radii R and 2R, having uniform volume charge densities  ρ1  and ρ2 respectively, touch each other. The net electric field at a distance  2R from the centre of the smaller sphere, along the line joining the centre of the spheres, is zero. The ratio   ρ1ρ2 CAN BE


A) -4

B) 3225

C) 3225

D) 4

Answer:

Option B,D

Explanation:

At point P

842021583_M3.JPG

 If resultant electric field is zero then,

KQ14R2=KQ28R3R

 ρ1ρ2=4

  At point Q

If resultant elecric field is zero  then

KQ14R2+KQ225R2=0
ρ1ρ2=3225(ρ1 must be negative )