Wire is wound on a square frame, 30 cm by 30cm, to form a coil of 7 tums. The fr

Question

Wire is wound on a square frame, 30 cm by 30cm, to form a coil of 7 tums. The frame is mounted on horizontal shalt through its center (perpendicular to the plane of the diagram). As shown in the figure. The coil is in clockwise rotation, with a period of 060 s. A uniform, horizontal, magnetic field of magnitude 0.40 T is present At a given instant, the plane of the coil forms a 60 degree angle with the horizontal, as shown. At that instant, what is the magnitude of the emf induced in the coil? 2.1 V 3.6 V 13 V 23 V 26 V A coil of 160 turns and area 0.20 m^2 is placed with its axis parallel t a magnetic field of initial magnitude 0.40 T. The magnetic field changes uniformly from 0.40 T in the + x direction to 0.40 T in the-x direction in 2.0 s. If the resistance of the coil is 16 ohm, at what rate is power generated in the coil? 25W 20 W 15 W 5.0 W 10 W The three loops of wire shown in the figure are all subject to the same uniform magnetic field B that does not vary with time Loop w oscillates back and forth as the bob in a pendulum, loop 2 rotates about a vertical axis, and loop 3 oscillates up and down at the end of a spring. Which loop. Or loop, will have an emf induced in them? loop 1 only loops 2 and 3 loop 2 only loops 1 and 2 loop 3 only

Explanation / Answer

11) 10 W is the correct ans.

The emf induced in the coil will be:

e = - N d(phi)/dt = - N A dB/dt

e = N A (B2 - B1)/t

e = 160 x 0.2 x [0.40 - (-0.40)]/2 = 12.8 Volts

induced current will be:

i = e/R = 12.8/16 = 0.8 A

Power will be:

P = i^2 R = 0.8^2 x 16 = 10.24 W = 10W(aprox)

Hence, 10 W is the correct ans.

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