Q.

A conducting square frame of side 'a' and a long straight wire carrying current I are located in the same plane as shown in the figure. The frame moves to the right with a constant velocity 'V'. The emf induced in the frame will be proportional to           [2015]


 

1 1(2x+a)2  
2 1(2x-a)(2x+a)  
3 1x2  
4 1(2x-a)2  

Ans.

(2)

Here, PQ=RS=PR=QS=a

Emf induced in the frame, ε=B1(PQ)V-B2(RS)V

=μ0I2π(x-a/2)aV-μ0I2π(x+a/2)aV

=μ0I2π[2(2x-a)-2(2x+a)]aV

=μ0I2π×2[2a(2x-a)(2x+a)]aV

   ε1(2x-a)(2x+a)