1. A coil is wrapped with 300 turns of wire on the perimeter of a circular frame
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Question
1. A coil is wrapped with 300 turns of wire on the perimeter of a circular frame (radius = 8.0 cm). Each turn has the same area. equal to that of the frame. A uniform magnetic field is turned on perpendicular to the plane of the coil. This field changes at a constant rate from 20 to 80 mT in a time of 20 ms. What is the magnitude of the induced emf in the coil at the instant the magnetic field has a magnitude of 50 ml? 2. A rod (length = 10 cm) moves on two horizontal frictionless conducting rails, as shown. The magnetic field in the region is directed perpendicularly to the plan of the rail and is uniform and constant. If a constant force of 0.6 N moves the bar at a constant velocity of 2.0 m/s. what is the current through the 12-omega load resistor?Explanation / Answer
1) Induced emf = change in magnetic flux/time
= N*A*(B2 - B1)/t
= 300*pi*0.08^2*(80-20)*10^-3/(20*10^-3)
= 18.1 volts
2) power dissipated = rate of workdone
I^2*R = F*v (here F is force and v is velocity)
I^2 = F*v/R
I = sqrt(F*v/R)
= sqrt(0.6*2/12)
= 0.316 A
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