why there is a repulsion between similar charges and attraction between unsimilar charges?

Asked by prabal singh | 23rd Apr, 2013, 11:57: AM

Expert Answer:

It can very easily be explained by using the fact that Every system has a tendency to lower it's energy.

For a system of 2 like/unlike charges (q1,q2), the energy of the system is given by the equation

U=k(q1)(q2)/r

where,

U=potential energy

k=constant for a medium(medium is one in which charges are kept eg air, water etc.)

q1, q= charges (including their sign, positive or negative)

r = dist. between charges

For U to be minimum, r should be maximum, everything else kept constant.

therefore, like charges move away to increase r. 

Incase of unlike charges one will be negetive and other positive. Let qbe negetive, so U=k(-q1)(q2)/r

Now, for U to be minimum, r should be minimum so charges attract.

Hence like charges repel and unlike attract.

 

Answered by  | 23rd Apr, 2013, 02:42: PM

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