Data Sheet

-27-
23. Motor Speed
Build the circuit to the left
and press and hold the press
switch (61). The LED (69) will
light indicating the motor has
voltage, the lamp (76) will light
dimly showing that current is
coming from the motor (95) and
the motor (95) will spin slowly.
The motor (95) spins slower in
this circuit than in project #8.
Remove the LED (69) from the
circuit and place the fan blade
on the motor (95) to make the
reduction in speed even more
obvious. Because the lamp (76)
has resistance, current owing
through the lamp (76) produces
a voltage drop and the motor (95)
gets less voltage due to Kirchhoff’s
second law. Less voltage on the
motor (95) explains why the fan
spins more slowly.
1st level
1st level
2nd level