Two concentric thin metallic spheres of radii R1 and R2 (R1 >R2 ) bear charges Q1 and Q2 respectively. Then the potential at r between R1 and R2 will be 1/(4πε0 ) times

Q: Two concentric thin metallic spheres of radii R1 and R2 (R1 >R2 ) bear charges Q1 and Q2 respectively. Then the potential at r between R1 and R2 will be 1/(4πε0 ) times

(a) $\large \frac{Q_1 + Q_2}{r} $

(b) $\large \frac{Q_1}{R_1}+ \frac{Q_2}{r} $

(c) $\large \frac{Q_1}{R_1}+ \frac{Q_2}{R_2} $

(d) $\large \frac{Q_2}{R_1}+ \frac{Q_1}{R_2} $

Ans: (b)

Sol: Let P be the point & O be the centre of concentric spheres , OP = r (say)

Potential at P  = Potential at P due to Q1 + Potential at P due to Q2

$\large V = \frac{1}{4\pi \epsilon_0} \frac{Q_1}{R_1} + \frac{1}{4\pi \epsilon_0} \frac{Q_2}{r} $

$\large V = \frac{1}{4\pi \epsilon_0} ( \frac{Q_1}{R_1} +  \frac{Q_2}{r}) $