Question

 

 

The figure is an edge-on view of a 14 cm diameter circular loop rotating in a uniform 3.8×10^-2 T magnetic field. I solved part a by using

 φ= B A cos θ = Bπr² cosθ = (3.8 x 10^-2) π (.07)2cos (0 degrees)= 5.8 x 10^-4 Wb and got correct answer, 

but having trouble finding the right answer for part B.  I used the same equation for part B and used cos (30)= got the wrong answer.  Is there another equation for finding the answer with the other angles?

Part A  What is the magnetic flux through the loop when is 0 degrees?

Express your answer to two significant figures and include the appropriate units.
=5.8×10⁻⁴ Wb
Correct

Part B  What is the magnetic flux through the loop when is 30 degrees?
Express your answer to two significant figures and include the appropriate units.
=

Part C
What is the magnetic flux through the loop when is 60 degrees?
Express your answer to two significant figures and include the appropriate units.
=

Part D  What is the magnetic flux through the loop when is 90 degrees?
Express your answer to two significant figures and include the appropriate units