14_Chapter 20 HomeworkCH20 Induced Voltages and Inductance

# 14_Chapter 20 HomeworkCH20 Induced Voltages and Inductance...

This preview shows page 1. Sign up to view the full content.

188 CHAPTER 20 20.33 (a) When a coil having N turns and enclosing area A rotates at angular frequency ω in a constant magnetic field, the emf induced in the coil is max max sin where tN B A == EE E 55.0 T B Here, is the magnitude of the magnetic field perpendicular to the rotation axis of the coil. In the given case, B µ = ; A ab π = where ( ) 10.0 cm 2 a = and ( ) 4. b = 00 cm 2; and rev 1 m 100 1 min 60.0    () in 0.5 s = 2 ωπ 2 rad s f Thus, 6 10.0 55.0 10 T 0.040 0 m 10.5 rad s 4    max E 0.100 m or 5 1.81 10 V 18.1 V max = E (b) When the rotation axis is parallel to the field, then 0 B = giving max 0 = E It is easily understood that the induced emf is always zero in this case if you recognize that the magnetic field lines are always parallel to the plane of the coil, and the flux through the coil has a constant value of zero.
This is the end of the preview. Sign up to access the rest of the document.

## This document was uploaded on 10/20/2011.

Ask a homework question - tutors are online