Question

1. Three charges Q, +q and +q and +q are placed at the vertices of a right angled isosceles triangle as shown. The net electrostatic energy of the configuration is zero, if Q is equal to :
(1) -q /√2 + 1
(2) -2q/2 + √2
(3) -q√2/√2+q
(4) + q
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Answer 1

Answer:

Correct option is

B

2+2−2q

Net electrostatic energy=0

UQq+Uqq+UQq=0

∴aQq+aq2+a2Qq=0orQ2+q2+Q=0

Q(2+1)=−q2orQ=(2+2)−2q