# Phy 132 - Assignment 9 through some closed surface ```Phy 132 - Assignment 9
A. 1. (a) No. (b) Gauss's law for magnetism. (c) ΦB through some closed surface
would not equal zero. (It would be proportional to the net “magnetic charge” within
the surface: You could have a net flux because of field lines coming from or going
to monopoles within the surface.)
2.
B. 1. Because you are integrating over area not time. If you are calculating Φ for a
particular instant, t is a constant. With a field which is the same everywhere,
⃑ = ∫
= BA = (t2 )(1 m2) = t2.
∫⃑
2.
C.
D.1. No – The battery would put a steady current through the primary, creating a
constant magnetic field. By Faraday’s law, the magnetic field must be changing to
induce an emf in the secondary coil.
2.
E. 1. B =
⁄
is the field coming from the coil. B = t2 is the field from the
approaching magnet. It’s two different fields you’re trying to set equal to each other.
(The right way to do it is with Faraday’s law, as on quiz A.)
2.
F.
```