A small circular loop of wire of radius a is located at the centre of a much larger circular wire loop of radius b. The two loops are in the same plane. The outer loop of radius b carries an alternating current I=I0cos(ωt). The emf induced in the smaller inner loop is nearly:
(1) 2πμ0I0⋅ba2ωsin(ωt)
(2) 2πμ0I0⋅ba2ωcos(ωt)
(3) πμ0I0ba2ωsin(ωt)
(4) aπμ0I0b2ωcos(ωt)