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A square loop of side a is placed in the same plane as a long straight wire carrying a current i. The centre of the loop is at a distance r from the wire where r > > a. The loop is moved away from the wire with a constant velocity v. The induced e.m.f. in the loop is |
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Answer» Solution :Magnetic field by the straight WIRE of current i ata DISTANCE r is B =`(mu_0 i)/(2pi r)` flux associated with the LOOP is `phi = BA = (mu_0 i)/(2pi r) a^2` ` therefore e = (-dphi)/(dt) = (-mu_0 )/(2pi) ia^2 (d)/(dt) (1/r) = (-mu_0)/(2pi) ia^2 = ((-1)/(r^2)) (dr)/(dt)` Hence the induced emf in the loop is `e = (mu_0)/(2pi) i (a^2)/(r^2) v ( because (dr)/(dt) = v)` |
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