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Question
A search coil having 2000 turns with area 1.5 cm2 is placed in a magnetic field of 0.60 T. The coil is moved rapidly out of the field in a time of 0.2 s. Calculate the induced emf in the search coil.
Solution
Data:
N = 2000
Ai = 1.5 cm2 = 1.5 × 10-4 m2
Af = 0
Bi = 0.60 T
Bf = 0
t = 0.2 s
Φ = B A
Formula:
Induced emf e = `-N (d phi)/(dt)`
= `-N (phi_f - phi_i)/dt`
Solution:
Initial flux,
Φi = NΦi = NBAi
= 2000 × 0.60 × (1.5 × 10-4)
= 0.18 Wb
Final flux,
Φf = NΦf = NBAf = 0, since the coil is withdrawn out of the field.
e = `-N (phi_f - phi_i)/dt`
e = `-(0 - 0.18)/0.2`
e = `(0.18)/0.2`
= 0.9 V
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