Cracking the SAT Physics Subject Test

Here’s How to Crack It

1. Since B is parallel to A, the magnetic flux is equal to BA.

ɸB = BA = (0.2T) · 30cm^2 ● = 6 ● 10−4 T × m^2

The SI unit for magnetic flux, the tesla·meter^2 , is called a

weber (abbreviated Wb). So ɸB = 6 × 10−4 Wb.

2. Since the angle between B and A is 60°, the magnetic flux
   through the loop is

ɸB = BAcos60° = (6 × 10−4Wb)(0.5) = 3 × 10−4 Wb

3. If the angle between B and A is 90°, the magnetic flux through
   the loop is zero, since cos 90° = 0.