Question

In a physics laboratory experiment, a coil with 250 turns enclosing an area of 11.4 cm2 is rotated in a time interval of 3.80×10⁻² s 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 earth's magnetic field at the lab location is 6.1×10⁻⁵ T.

Part A

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

Express your answer using two significant figures.

Φ1

Φ 1

=

nothing

Wb

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Part B

What is the magnetic flux through each turn of the coil after it is rotated?

Express your answer using two significant figures.

Φ2

Φ 2

=

nothing

Wb

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Part C

What is the average emf induced in the coil?

Express your answer using two significant figures.

E

E

=

nothing

V

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Answer 1

given
N = 250 turns
A = 11.4 cm^2
= 11.4*10^-4 m^2
delta_t = 3.80*10^-2 s
B = 6.1*10^-5 T
A)

the magnetic flux through each turn of the coil before it is rotated,

phi_1 = A*B*cos(theta)

= 11.4*10^-4*6.1*10^-5*cos(0)

= 7.0*10^-8 Wb

B) the magnetic flux through each turn of the coil after it is rotated,

Phi_2 = 0A*B*cos(theta)

= 11.4*10^-4*6.1*10^-5*cos(90)

= 0 Wb

C) Average induced emf = total change in magnetic flux/time taken

= N*(phi_1 - phi_2)/delta_t

= 250*(7.0*10^-8 - 0 )/(3.80*10^-2)

= 4.6*10^-4 V