Data Sheet

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21. Lamp, LED and Motor

Series-Parallel Connection (I)

Build the connection. The lamp (76) and the LED (70)

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 nger. This is because the

voltage drop across the LED (70) (at least 1.5 volts)

reduces the voltage across the motor (95), limiting the

current owing through the motor (95) and which

makes it more difcult to start the motor spinning (like

in project 19). The lamp (76) lights because it is in

parallel with the motor (95) & LED (70).

22. Lamp, LED, and Motor

Series-Parallel Connection (II)

Build the circuit, you will nd that the LED (70) 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 nger. This is

because the lamp (76) and motor (95) are each

connected in series with the LED (70), and voltage drop

across the LED (at least 1.5 volts) reduces the voltage

across the motor (95) and lamp (76), limiting the current

owing through the motor (95), making it more difcult

for the motor to start spinning and limiting the current

through the lamp (76), preventing it from lighting.

1st level

Level block

1st level

EBX120_Manual_042817 5/17/2017 10:54 AM Page 27