Question

PROBLEM 3 In the figure a circular loop is shown, which is inside a uniform magnetic field of magnitude 0.200 T that is pointing out of the page. The radius of the loop is initially equal to 30.0 cm, and at t = 0 starts to decrease at a constant rate of 4.00 cm / s until t = 4.00 s. a) Find the magnitude of the emf induced in the loop at t = 2.00 s. b) What is the direction of the induced current at t = 2.00 s and why? c) Find the induced emf in the loop at t = 5.00 s.

Answer 1

a B = 0.200 T (out of page) initial readius of loop = R330.00m -4.00 Crys o dt :: rattius at a perticulare time t utk (R - 4.00 +Jem (30.0-4:00t) cm (30.0-4.00t) x 102 M Now & (t)- 18. A = B 'A COSO - BA 06 - 01200 * {(30.0 -4.004) *093? 0.200 T (30-4t) x 10-4 4 es -do = at есе) 0.2007 X 2 x 10 (30-4+) (-4) 5,024 x10-4 (30-47) t= 2.00 5.024 X10-4 ( 30-4+2) 110.528 x 10-4 valt at e Ct). b since radius of loop us decreasing so direction of Induced current is such that ut must oppose the door decrease in radius hence flux : direction uh anti Glockarise j should be direction. so that

resulting force on every part of cirumference us radially out wards c) at t-5.00 sec there is no change in radius hence No Char in flux passing through loop No induced EMF at &-5.00 sec EMF
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