Question

Three conducting spherical shells have charges q, − 2q and 3q as
shown in figure. Find electric potential at point P as shown in figure.

JEE Mains

Answer 1

Answer:

A

Explanation:

Solution :

Potential P,

<br> =(kq)/r-(k(2q))/r+(k_(3q))/(3R)

=kq(1/R-1/r)

k=1/(4piepsilon_0)

Answer 2

Answer:

Potential at P is :- $\large 3Kq/5R$

Explanation

Potential at p will be due to shell 1 shell 2 and outermost shell

As P is outside two shell than

Potential of shell 1 at P= $2Kq/5R$

Potential of shell 2 at P= $2K(-2q)/5R$

Potential at P due to outer shell=K(3q)/3R

Now add all the potentials to get total potential

$\frac{2Kq}{5R}- \frac{4Kq}{5R}+\frac {Kq}{R}=\large 3Kq/5R$

Additional information

• potential inside a shell is constant every where
• Electric field inside a shell is zero everywhere