AIIMS 2017 Physics Question Paper for free online practice with solutions

Let q charge is situated at the mid position of the line AB. The distance between AB is x. A and B be the positions of charges Q and Q respectively.

Let AC=

x

2

,BC=

x

2

The force on A due to charge q at C,

→

F

CA=

1

4πε0

.

Q.q

(x∕2)2

along

→

AC

The force on A due to charge Q at B

→

F

AB=

1

4πε0

.

Q2

x2

along

→

BA

The system is in equilibrium, then two oppositely directed force must be equal, i.e., total force on A is equal to zero.

→

F

CA+

→

F

AB=0 ⇒

→

F

CA=−

→

F

AB

1

4πε0

.

4Q.q

x2

=

−1

4πε0

.

Q2

q

⇒q=−

Q

4