Load in a Circuit

How do many loads affect electric current in a circuit?

Open Ended

Form a Hypothesis

You can compare the amount of electric current in circuits by observing light bulbs. A very bright bulb has more current than a dim bulb. How do connecting bulbs in a series circuit affect electric current in the circuit?

Record your hypothesis below in the form “If you add light bulbs to a circuit, then . . .”.

You will need

• 3 sockets

• 3 light bulbs

• 2 battery holders

• 2 AA batteries

• 4 wires

Open Ended

⋅ Insert the battery into the battery holder. Screw the light bulbs into the bulb sockets.

⋅ Use two wires to connect the battery holder to the bulb socket.

⋅ Observe Look at the light bulb. Does it shine brightly or is it dim? Record your observations below

Open Ended

Experiment Disconnect a wire from one side of the light bulb. Make a series circuit by connecting another socket and light bulb with a piece of wire.

Observe Are the two bulbs brighter or dimmer than the bulbs in the first circuit?

Experiment Add the third bulb and socket to the series circuit.

How bright are the light bulbs now?

Record your observations.

Open Ended

Draw Conclusions

How did adding bulbs to the circuit change the brightness of the bulbs?

Open Ended

Infer How did adding bulbs change the amount of current in the

circuit?

Open Ended

Adding bulbs increases the amount of resistance in a circuit.

Write a new hypothesis. “If you increase the resistance in a circuit,

then . . .”