According to the given problem,
We know that,
Induced
EMF   E   =   -dφ/dt   =   -
B *dA/dt   =   - B * (A2
-A1) / dt   =   B
*(A1Â Â Â -Â Â Â A2)
/dt
Given,
B   =   Magneticfield   =   0.355
T,  Â
   In reshaping of
wire, circumference ( totallength) must remain the same.
   When wire is in
four
loops,   totallength   L   =
4 *(2 * π *r1 )  = 8 *π *0.55 =
13.823 m
   When wire is in two
loop   L   = 2(2 *π *r2)
=>Â Â Â r2Â Â Â = 13.823/4*Ï€
= 1.1 m
   Initialarea   A1   =   No.of
loops * π *r12   = 4 *3.14
*0.552Â Â Â = 3.80133 m2
   Finalarea   A2   =
No.of loops* π*r22   = 2*
3.14*1.12Â Â Â = 7.6027 m2
   Hence
inducedEMFÂ Â Â EÂ Â Â =Â Â Â 0.355
*( 3.80133Â Â -Â Â Â 7.6027) /0.128
=Â Â Â Â - 10.543 V
   - ve sign idicates
the direction of inducedEMF.
