BUT IN CASE OF (WHEN CURRENT DOES NOT FLOW)POTENTIAL DIFFERENCE IS ZERO FOR A CHARGE SO WORK DONE SHOULD BE ZERO ,,,AND FOR WORK DONE TO '0' FORCE (F)*DISPLACEMENT(d)*COS THETA SHOULD BE Fdcos90(so force is acting perpendicularlyto displacement)?If AM I RIGHT THEN HOW THIS MOTION IS EXECUTED?

Asked by abinash.gupta003 | 29th May, 2017, 02:39: PM

Expert Answer:

  • Work done is a concept arising from various cases. The work done that you have mentioned arises due to a mechanical force acting on the object. 
  • In the case of charges, the work done arises due to a change of potential difference.
  • So, there is no physical/mechanical force acting on the charges. Hence, it would be incorrect to use W = Fscosθ for the flow of charges.
  • On the hindsight, W = FScosθ = 0 means three cases: F = 0, s = 0 or θ = 90. So, W = 0 does not mean that the angle between force and displacement is 90. It means that the potential difference is zero due to which the force itself is zero. Hence, W = 0.

Answered by Romal Bhansali | 30th May, 2017, 10:13: AM

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