Verified Solution • 2025–26 Session moderate

QJEEAdv08Ph99f4: JEE Advanced 2008 Physics - Class 12 JEEAdv08Ph99f4 Solution: The electric field at r = R is :

The electric field at r = R is :

Step-by-Step Verified Solution

IIT-JEE 2008 Paper 2 Offline Physics - Electrostatics Question 11 English Explanation

At $r = R$ ,

By applying Gauss law,

$ϕ = \frac{q_{e n c l o s e d}}{ε_{0}}$

$\Rightarrow \oint E . d s = \frac{q_{e n c l o s e d}}{ε_{0}}$

$\Rightarrow E \oint d s = \frac{q_{e n c l o s e d}}{ε_{0}}$

$\Rightarrow E .4 π R^{2} = \frac{Z e}{ε_{0}}$

$\Rightarrow E = \frac{1}{4 π ε_{0}} \frac{Z e}{R^{2}}$

i.e., $E μ \frac{1}{R^{2}}$

Here, electric field is independent of 'a'.