AMU Engineering 2018 solved paper Solved Paper

r= distance between two identical spheres,
and Q= charge on spheres A and B.
F=

1

4πε0

.

Q2

r2

........(i)
When a third identical sphere ' C ' is first touches with A, then the value of charges on A and C will be

Q

2

.
Again, when C touches with B, then value of charge on B and C=

Q 2 +Q

2

=

3Q

4

Now, the electrostatic force between spheres A and B
F′=

1

4πε0

.

Q

2

.

3Q

4

r2 =

3

8

.

1

4πε0

.

Q2

r2

=

3

8

F‌‌‌‌ [from Eq.(i)]