Question
Question: If a small sphere of mass m and charge q is hanged from a silk thread at an angle q with the surface...
If a small sphere of mass m and charge q is hanged from a silk thread at an angle q with the surface of a vertical charged conducting plate, then for equilibrium of sphere the surface charge density of the plate-
A
qε0mgtanθ
B
qε02mgtanθ
C
e0 mg q tan q
D
3qε0mgtanθ
Answer
qε02mgtanθ
Explanation
Solution

T sin q = qE …(1)
T cos q = mg …(2)
tan q = = 2ε0mgqσ
s = q2ε0mgtanθ