Download Motor Effect Objective Background

Motor Effect
chapter 12
lesson 5
Objective
you will be able to qualitatively and
quantitatively describe the operation of an
electric motor.
Background
Recall that when a moving charge interacts with
a fixed magnetic field it produces a force.
(Third Left Hand Rule)
If the moving charges are in a wire, then the
wire will move.
A motor takes advantage of this movement and
makes it do work.
What factors affect the magnitude of the force?
Formula:
Example
A wire 0.10 m long carrying a current of 2.0 A
is at right angles to a magnetic field. The
force on the wire is 0.040 N. What is the
magnitude of the magnetic field?
Example
A copper wire 40 cm long is placed in a
magnetic field of 0.15 T and weighs 0.35 N.
The wire remains suspended in the field.
What is the magnitude of the current in the
wire?
Assignment
Read p.602-608
SNAP p.120 all
Answers to Even
2: 1.60 x 10-4 N [E]
4: 1.30 x 10-13 N [W]
6: 1.6 T [E]
8: 0.450 N
10: 36 V
12: 1.52 T