Answer to Question #212612 in Electricity and Magnetism for Joramichi

Question

The SkyDome in Toronto, Canada has one of the world’s largest retractable roof. Its area is

32, 000 m2

, and it takes 20 min for the roof to fully retract. If you have a coil wired through the

roof, how many turns do you need to wind up your coil for you to generate an induced emf of

120 V? Assume that a uniform magnetic field with a strength of 3.0 x 10-2 T passes through

the coil parallel to its axis.

Answer 1

$\xi=-n\frac Фt=Sn\frac Bt,\implies$

$n=\frac{\xi t}{SB},$

$n=\frac{120\cdot 20\cdot 60}{32000\cdot 0.03}=150.$