Page 59 - Electric Machinery Fundamentals
P. 59
lNTRODUC nON TO MACHINERY PRINCIPLES 35
+ X B
~~TX
X X
+::
:XB
X X X
eimJ
X X X X
- v
X X X X
FIGURE 1-17
A conductor moving in the presence of a
X X X X magnetic field .
• • • •
B
•
•
•
•
•
FIGURE 1-18
The conductor of Example 1-9.
Solution
The direction of the quantity v x B is down. The wire is not oriented on an up-down line,
so choose the direction of I as shown to make the smallest possible angle with the direction
of v X B. The voltage is positive at the bottom of the wire with respect to the top of the
wire. The magnitude of the voltage is
eind = (v X B) . I (1-45)
= (vB sin 90°) I cos 30°
= (10.0 mls)(O.5 T)( I.O m) cos 30 0
= 4.33 V
The induction of voltages in a wire moving in a magnetic field is funda-
mental to the operation of all types of generators. For this reason, it is called
generator action.
