A square- shaped copper coil has edges of length 50cm and contains 50 turns. It is placed perpendicular to 1.0 T magnetic field. It is removed form the magnetic field in 0.25 s and restored in its joriginal place in the next 0.25 s. Find the magnitude of the average emf induced in the loop during (a) its removal, (b) its restoration and (c) its motion.

Explanation

(a) during removal,
`phi_1=BA`
`=1xx50xx0.5xx0.5`
`25xx0.5=12.5 T-m^2`
` phi_2=0, t=0.25s`
`e=(-d phi)/(dt)=(phi_1-phi-2)/(dt)`
`=12.5/0.25=(125xx10^(-1))/(25xx10^(-2))=50 V.`
`(b) During its restoration `
`phi_1=0,`
`phi_2=12.5 Tesla-m^2`
`t=0.25s`
`e=(12.5-0)/(0.25)=50V.`
`(c ) During the motion
`phi_1=0,`
`phi_2=0`
`e=(d phi)/(dt)=0`.