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The amount of current that leaves the positive side of the cell is equal to the current that returns to the negative side. No current is used up. On the right is an example of a circuit with 2 cells and 2 lamps.

Important Points

• The Brightness is the same.
• An ammeter will give the same reading at every point around the circuit.
• If one bulb blows or breaks they all do because this will cause a gap in the flow of current.

However, the total current may be slowed down or reduced by objects placed in the circuit because they have a resistance.

The amount of resistance is measured in Ohms. The greater the resistance, the less current can flow. The current is still the same at any place around the circuit, there is just less of it.

• With a ratio of 1 cell: 1 lamp, the lamp shines with "normal brightness"
• If there are more lamps than cells their brightness is "less than normal" (more resistance, less current)
• If there are less almps than cells their brightness is "greater than normal" (less resistance, more current)

Current (I) and Resistance (R)

Current and resistance have an effect on each other. They obey a law called "Ohms Law" which simply tells us that as the resistance goes up, the amount of current goes down OR as the resistance goes down, the amount of current goes up.

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