a) The component of the external magnetic field along the central axis of a 50-t

Question

a) The component of the external magnetic field along the central axis of a 50-turn coil of radius 5.1 cm decreases from 1.8 T to 0 T in 3.8 s.

If the resistance of the coil is 2.8 , what is the magnitude of the induced current in the coil? (Answer in A)


b) The armature of an ac generator is a rectangular coil 1.5 cm by 5.4 cm with 73 turns. It is immersed in a uniform magnetic field of magnitude 0.45 T. If the amplitude of the emf in the coil is 17.0 V, at what angular speed is the armature rotating?
(Answer in rad/s)

Explanation / Answer

N = 50 turns, r = 5 cm , B1 =1.8 ,B2 =0 T, t = 3.8 s, R =2.8 ohms

(a) from faradays law

induced emf V = -d(phi)/dt

V = NA(B1 - B2)/t

From ohms law V = IR

IR = NA(B1 - B2)/t

I*2.8 = 50*3.14*0.05^2(1.8 - 0 )/3.8

I =0.066 A

(B) Therefore,

d/dt = -BA sin(t)

and,

E(max) = N B A

17 = 73*0.45*1.5*10-2m*5.4*10-2*

= 638.9 rad/sec

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.