Faraday’s law?

Question

You hold a thin gold wedding ring with an inside radius of 1 cm, such that the plane of the ring is perpendicular to the Earth's magnetic field. At your location it has strength 5.5×10−5 T. What is the emf induced in the ring if you turn it in one-tenth of a second to be parallel to the field (that is, you make the area vector of the ring perpendicular to the field) (V)?

Answer 1

Here's my attempt:

E = ε/(2πr) = -(r/2)*(dB/dt)  -->  ÃŽÂµ = -(r/2)*(dB/dt)*(2πr)

ε = -[(0.01m)/2] * [(5.5×10^-5T)/(0.1s)] * [2*π*(0.01m)]

...

ε = -1.73×10^-7 (T*m²)/s = -1.73×10^-7 V

Units conversion:

T*(m²/s) = {N/[(C/s)*m]}*{m²/s} = (N*m)/C = J/C = V

Dost thou concur?