Question

two points charges,each of the 3 into 10 to the power minus 9 c. located at two. virtices of an equilateral triangle of 20 cm how much work must be done to bring a charge of the third corner of triangle from the infiniti
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Answer 1

Answer:

Let a be the side of equilateral triangle.

• Initial the potential energy of the system is U

i

=

4πϵ

0

1

r

12

q

1

q

2

=

4πϵ

0

1

a

qq

=U

When another charge charge q bring at the third vertex of triangle, the potential energy of the system is

U

f

=

4πϵ

0

1

r

12

q

1

q

2

+

4πϵ

0

1

r

13

q

1

q

3

+

4πϵ

0

1

r

23

q

2

q

3

=

4πϵ

0

1

a

qq

+

4πϵ

0

1

a

qq

+

4πϵ

0

1

a

qq

=

4πϵ

0

1

a

3qq

=3U

• The work done = change in potential energy =U

f

−U

i

=3U−U=2U