A coil with an average diameter of 0.02 m is placed perpendicular to a magnetic field of 6000 T. If the induced e.m.f. is 11 V when magnetic field is changed to 1000 T in 4 s, what is the number of turns in the coil ?

Explanation

Given, radius of coil, `r=(0.02)/(2)=0.01m`
`B_(1)=6000T,B_(2)=1000T,t=4s,e=11V`
`"emf,e"=N((phi_(2)-phi_(1)))/(t)=NA(B_(2)-B_(1))/(t)`
`=Npir^(2)(B_(2)-B_(1))/(t)`
`11=N.(22)/(7)xx(0.01)^(2)xx((6000-1000))/(4)`
Number of turns,
`N=(11xx7xx4)/(22xx(0.01)^(2)xx5000)=28`