The cross-section area of an adjustable single loop is reduced from 1.2 m^2 to 0.4 m^2 in 0.25 seconds. What is the average emf that is induced in this coil if it is in a region where B = 1.5 T downward, and the coil's plane is perpendicular to B?
magnetic flux through coil area =1.2 sq m
`=1.8 ` Wb
change in magnetic flux=`Deltaphi`
so we have
`Delta t=0.25 `