shows a conducting disc rotating about its axis in a perpendicular magnetic field B. A resistor of resistance R is connected between the centre and the rim. Calculate the current in the resistor. Does it enter the disc or leave it at the centre? The radius of the disc is 5.0 cm , angular speed `omega = 10 rad/s, B = 0.40 T` and `R = 10 Omega`.

Explanation

Here B=0.10T, omega=10 rad//s`
`R=10 Omega, r=5 cm=0.5m`
`Considering a rod rotating with the same omega,`
`theta =(1/2)xxomega=(0.05)/(2)xx10`
`theta =Blv`
`=0.40xx(0.05/2)xx10xx0.05`
`=5xx10^(-3)V.`
`i=R=(theta/R)`
`=(5xx10^(-3))/(10)=0.5 mA.`
`It leaves from the center.`.