Class 12 NEET Physics Electrostatics Questions Part 1

The situation is as shown in the figure. Let two equal charges Q each placed at points A and B at a distance r apart. C is the centre of AB where charge q is placed. For equilibrium, net force on charge Q=0
∴

1

4πε0

QQ

r2

+

1

4πε0

Qq

(r∕2)2

=0

1

4πε0

Q2

r2

=−

1

4πε0

4Qq

r2

or Q=−4q or q=−

Q

4