The magnetic field and a current-carrying frame
Answers are for parents and teachers.
1
A surface of 0.25 m² is perpendicular to B = 2 T. What is the flux in mWb?
500
2
A frame normal makes 60° with B = 0.6 T and S = 0.1 m². What is the flux in mWb?
30
3
N = 20, I = 3 A, B = 0.1 T, S = 0.05 m², α = 90°. What is the torque in N·m?
0.3
4
What principle do the moving-coil ammeter and the DC motor have in common?
In both, a torque acts on a current-carrying frame in the field of a permanent magnet.
5
Why is magnetic flux a scalar while magnetic induction is a vector?
B has a direction (tangent to the field lines); the flux is a single number calculated using the cosine of the angle between B and the surface normal.