Exercise 27.16 A circular wire loop 55 cm in diameter has resistance 120 and lie

Question

Exercise 27.16 A circular wire loop 55 cm in diameter has resistance 120 and lies in a horizontal plane A uniform magnetic field points vertically downward, and in 25 ms it increases linearly from 5 0 mT to 55 mT Part A Find the magnetic flux through the loop at the beginning AE mwb Submit My Answers Give Up Part B Find the magnetic flux through the loop at the end of the 25 ms penod mwb Submit My Answers Give Up Part C What's the loop current dunng this time? Express your answer with the appropriate units,

Explanation / Answer

diameter = 55 cm,

so r = 27.5 cm = 0.275 m

A = pir^2 = pi(0.275)^2 = 0.2375 m^2

a)

Flux = Field x Area ( = BA )

= 5 x 10^-3 x 0.2375 = 1.1873 x 10^-3 Wb = 1.1873 mWb

b)

= BA = 55 x 10^-3 x 0.2375 = 13 mWb

c)

Induced emf = rate of change of flux = (flux change)/time = (13 mWb - 1.1873 mWb) / (25 x 10^-3) =0.4725V

= Emf/R = 0.4725/120 = 3.93 mA

d)

Using Lenz's Law, the induced current will produce a field which opposes the increasing field. The field from the current therefore points upwards Using the right hand grip rule means current is anticlockwise when viewed from above the ring.

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