Question

1. The armature of an ac generator is a circular coil with 292 turns and radius 4.6 cm. When the armature rotates at 939 rpm, the amplitude of the emf in the coil is 21.3 V. What is the strength of the magnetic field (assumed to be uniform)?

2. The armature of an ac generator is a rectangular coil 27.0 cm by 17.9 cm with 294 turns. It is immersed in a uniform magnetic field of magnitude 3.0 T. If the amplitude of the emf in the coil is 32.7 V, at what angular speed is the armature rotating? Round your answer to two significant figures.

A square loop of wire, 0.55 m on each side, has one edge along the positive z-axis and is tilted toward the y-z plane at an angle of 30.0° with respect to the horizontal (x-z plane). There is a uniform magnetic field of 0.22 T pointing in the positive x-axis direction. (a) What is the flux through the loop? (b) If the angle increases to 60°, what is the new flux through the loop? (c) While the angle is being increased, which direction will current flow through the top side of the loop? 30.0 Wb (c) The current in the top side of the loop must flow in the (select)direction.

Answer 1

a.) ϕ = BAsin 30

= 0.22*(0.55^2)sin(30)
= .003327 Wb

b.) ϕ = BAsin 60
= 0.22*(0.55^2)sin(60)

=0.05763 Wb

c.) -ve z direction