In a physics laboratory experiment, a coil with 180 turns. Each turn of the coil

Question

In a physics laboratory experiment, a coil with 180 turns. Each turn of the coil encloses an area of 17cm2 . The coil is rotated from a position where its plane is perpendicular to the earth's magnetic field to one where its plane is parallel to the field. The rotation takes 5.0x10^-2s . The earth's magnetic field at the location of the laboratory is 6.0x10^-5T .

Part A

What is the magnetic flux through one turn of the coil before it is rotated?

Express your answer using two significant figures. Answer in Wb

Part C

What is the average emf induced in the coil as it is rotated from the perpendicular to the parallel orientation?

Express your answer using two significant figures. Answer in mV

Explanation / Answer

The avg. emf induced in a coil with "N" turns is the rate of change of flux thru the coil;

E = -N[(flux)f - (flux)i]/t

The flux is ; BACos(a) , where "a" is the angle between "B" and a perpendicular line to the area "A"

Initially you have max flux thru "A" because the "plane" of "A" is perpendicular to "B" ,which means the perpendicular line to "A" is parallel to "B" , so angle "a" = 0 deg.

(flux)i = BACos(0) = BA

Finally you have zero flux thru "A" because the field line slide over "A" rather then penetrate. The angle "a" = 90 deg.

(flux)f = BACos(90) = 0

So the emf reduces to;

E = N(BA)/t

= (150)(6.7x10^-5)(12.2x10^-4)/(3.2x10^-2)

= 383 x 10^-6 volts

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