99 Percentile Qs Bank for JEE MainPhysicsElectrostatics
Four electric charges +q,+q,-q and -q are placed in order at the corners of a square of side 2 r . The electric potential at a point midway between the two negative charges is
Options
- A1 4 ₀ 2 q r [1- 5 ]
- B1 4 ₀ 2 q r [ 1 5 +1 ]
- C1 4 ₀ 2 q r [ 1 5 -1 ]
- DZero
Correct answer
C. 1 4 ₀ 2 q r [ 1 5 -1 ]
Step-by-step solution
Consider the following figure: D P=P C=r and A P=B P= A D^2+D P^2 = r^2+(2 r)^2 = 5 r Potential at P is V_P= 1 4 ₀ [ q A P + -q C P + -q D P + q B P ] V_A= 1 4 ₀ V_A [ -q r + +q r 5 + +q r 5 L + -q r ]= 1 4 ₀ 2 q r ( 1 5 -1 )