A rectangular wire loop of sides 8 cm and 2 cm with a small cut is moving out of a region of uniform magnetic field of magnitude 0.3T directed normal to the loop. What is the emf developed across the cut if the velocity of the loop is `1cms^(-1)` in a direction normal to the (a) longer side, (b) shorter side of the loop? For how long does the induced voltage last in each case?

Explanation

a. `B=0.3T," "l=8xx10^(-2)m,v=1xx10^(-2)ms^(-1)`
`varepsilon=Blv=0.3xx10^(-2)xx8xx10^(-2)=0.24mV` `v=(l)/(t) therefore t=(l)/(v)=(2cm)/(1cm//s)=2sec`
b. The emf developed when the velocity of loop is in the direction normal to the shorter side
`varepsilon=0.3xx10^(-2)xx2xx10^(-2)=0.06mV`
`t=(l)/(v)=(8cm)/(1cm//s)=8sec`