Q: Charge Q is distributed to two different metallic spheres having radii R and 2 R such that both spheres have equal surface charge density. Then charge on large sphere is
(a) 4Q/5
(b) Q/5
(c) 3Q/5
(d) 5Q/5
Click to See Answer :
Ans: (a)
Sol: If q1 , q2 are the charges on sphere of radii R and 2 R respectively.
Since , σ1 = σ2
$\displaystyle \frac{q_1}{4\pi R^2} = \frac{q_2}{4\pi (2R)^2} $
$\displaystyle q_2 = 4 q_1$
As $ q_1 + q_2 = Q $
$ 5 q_1 = Q $
$ q_1 = \frac{Q}{5} $
$ q_2 = \frac{4Q}{5} $