2 What happens to the brightness of the bulbs when you unscrew one bulb in the circuit?
3 What does the brightness of the bulbs tell you about the amount of current flowing in the circuit? Explain your observations.
4 5
Suggest a way to increase the brightness of the bulbs.
CONCLUSION Write a conclusion for the investigation about the effects of resistors in series circuits.
DISCUSSION
From the investigation you will have noticed that the more resistors were added in series into the circuit, the dimmer the light bulbs became. This means that as more resistors are added in series, the current becomes less. When one of the resistors in series was disconnected, all of the resistors went out.
Total: 20 marks New word
parallel circuit – a circuit with more than one path along which current can flow
Parallel circuits
Components of circuits, such as cells and resistors, can be connected so that there is more than one path along which the current can flow. We call these parallel circuits. In parallel circuits the current is divided between the components of the circuit. Look at the diagram of a circuit alongside which has light bulbs connected in parallel. Notice that each light bulb has its own connection to the cells in the circuit. This means that each light bulb has its own supply of current and does not have to share the current with the other light bulbs.
In Figure 3 the current has two paths along which it can flow. The current flows from the positive end of the battery and then it divides so that some of the current flows through one light bulb and some through the other light bulb. The current rejoins and flows back to the battery.
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Figure 3 Bulbs connected in parallel 120 Topic 3 Series and parallel circuits
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