Question

27. The work which is required to be done to make an
arrangement of four particles each having a charge
+q such that the particles lie at the four corners
of a square of side a is
(1) (4+√2)kq^2÷a
(2)4kq^2÷a
(3) (2+√2)kq^2÷a
(4) 2kq^2÷a​

Answer 1

Explanation:

charges are present on corners B,C,D,E.

total electric force will be along the direction

OA

magnitude of force = 2

4πϵ

0

1

a

2

q

cos36

∘

−2

4πϵ

0

1

a

2

q

cos72

∘

=

4πϵ

0

1

a

2

q

Answer 2

Explanation:

Answer is OPTION 1

U =

$4k q ^2 \a \: + 2kq {}^{2} \a \sqrt{2}$

W = U