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Himanshu posted an Question
July 19, 2020 • 07:19 am 30 points
  • IIT JAM
  • Physics (PH)

Electricity

yesterday also I asked similar type of question but it is quite different answer that i learned. According to me answer should be C but it's A& D How ???

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    Dhairya sharma

    dear see the some conclusion from electrodynamics: 1.E and V both can be zero. 2.If V=0, E may or may not be zero. 3.If E=0, V may or may not be zero. In the options only 1 and 2 conclusions are given. So ans is a and d.

    eduncle-logo-app

    if u want i can provide example of these

    eduncle-logo-app

    like field is zero in conductor but not potential

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    Ruby negi best-answer

    yeah, somnath sir is right.. If E is zero, V may or may not be zero. also when V is zero, E also may or may not be zero .. and the examples are also correct according to the situation...

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    Somnath Best Answer

    It depends on what you mean when you say V=0V=0. In the context of the equation: E=−∇V which holds specifically in electrostatics V is a scalar field, meaning that it is actually a function which assigns every point in space a scalar value. E is a vector field, which assigns a vector to every point in space. Thus, both the electric field and the potential are dependent upon position. This can be shown more explicitly as: E⃗ (r)=−∇V(r) where r is a position vector. Now, if V(r)=0 for all r then certainly the gradient is also zero everywhere, and thus, the electric field is zero everywhere. On the other hand V(r) may equal zero for only some r. For example, at the point P midway between two point charges, one with charge +q and the other with charge −q the potential is zero but field is non zero. Because if you move even slightly away from this point, the potential is non zero. The fact that the potential is changing at point P indicates that the gradient at this point is non zero. Thus, the electric field at P is non zero, even though the potential itself is zero at P. Similarly at the midpoint between two same charge q potential V is non zero but field E is zero. Thus we may conclude that 1.E and V both can be zero. 2.If V=0, E may or may not be zero. 3.If E=0, V may or may not be zero. In the options only 1 and 2 conclusions are given. So ans is a and d.

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