Question

point
15. The sum of two charges is 'Q' separated with a distance 'r'. What should be the magnitude of each charge so that
force between them is maximum?
0 0
Q
(b)
99
2 2
(c)
29
4 2
(d)
2 2
4​

Answer 1

Answer:

Let one part of the charge be q.

Thus other part of the charge is Q−q

Electrostatic force between them F=

r

2

kq(Q−q)

For maximum force,

dq

dF

=0

∴

dq

d

(

r

2

kq(Q−q)

)=0

Or

dq

d

(qQ−q

2

)=0

Or Q−2q=0 ⟹q=

2

Q

Hence force between them is maximum if the tqo parts have charge Q/2 each.

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