Question

shows a conducting loop being pulled out of a magnetic field with a speed v. Which of lthe four plots shown in may represent the power delivered by the pulling agent as a function of the speed v ?
A. a
B. b
C. c
D. d

Answer 1

Correct Answer - B

Induced emf = Bvl
Induced current, `i=(Bvl)/(R)`
Magnetic force on loop, `F_(m)=Bil=(B^(2)vl^(2))/(R)`
Since, loop is moving with constant speed,
`rArr" "F=F_(m)`
Input power, P = F.v = Fv `=(B^(2)v^(2)l^(2))/(R)`
P versus v graph will be like,
`y prop x^(2)` (parabola, open upward)