well its not dat tuff.......
flux due to outer circle(φ)=μi2b*πa2
emf=dφdt
the current in inner circle(i)=emfR
thus charge in inner coil =idt=ans given .............(a)
two concentric and coplanar coils have radii a & b (>>a) as shown in figure.
Resistence of the inner coil is R.
Current in the outer coil is increased from o to i, then the total charge circulating in the inner coil is:
a) \mu(pie) i a22 R b
b) \mu i a b2 R
c) \mu i a (pie) b22 a R
d) \mu i b2 (pie) R
(the ans given is a)
sandipan ..are u sure the ans doesnot have pi...in the numerator.....
or
its me who's makin da mistake
well its not dat tuff.......
flux due to outer circle(φ)=μi2b*πa2
emf=dφdt
the current in inner circle(i)=emfR
thus charge in inner coil =idt=ans given .............(a)