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21. Lamp, LED and Motor
Series-Parallel Connection (II)
Build the connection. The lamp (76) and the LED (69)
will turn on, and the motor (95) will spin. If the motor
does not spin, you may need to get it started by
spinning the shaft with your finger. This is because
the voltage drop across the LED (at least 1.5 volts)
reduces the voltage across the motor (95), limiting
the current flowing through the motor (95), making it
more difficult for the motor to start spinning (like in
project 19). The lamp (76) lights because it is in
parallel with the motor (95) & LED (69).
22. Lamp, LED, and Motor Series-
Parallel Connection (III)
Build the circuit, you will find that the LED (69) lights and
the motor (95) spins very slowly, but the lamp (76) does
not light. If the motor does not spin you may need to get
it started by spinning the shaft with your finger. This is
because the lamp (76) and motor (95) are each
connected in series with the LED (69), and voltage drop
across the LED (at least 1.5 volts) reduces the voltage
across the motor (95) and lamp (76), limiting the current
flowing through the motor (95), making it more difficult
for the motor to start spinning and limiting the current
through the lamp (76), preventing it from lighting.
1st level
1st level
Level block
Level block
1st level
1st level
E-BLOX_2X_Model_115_042517 5/17/2017 10:58 AM Page 27
