Page 327 - Canadian BC Science 9

Voltage and Current in a Series Circuit
The people on the waterslide represent the electrons that flow through the circuit. A person has more potential energy at the top of the stairs than at the bottom. Suppose the staircase has 12 steps. A person who slides from the top of the slide to the bottom will “lose” all 12 steps before returning to the bottom of the stairs.
In an electric circuit, the charge that leaves a 12 V battery “loses” all 12 V before it returns to the battery. These losses occur on loads such as light bulbs or resistors, which transform the electrical energy into other forms of energy. Each load in the series circuit loses a portion of the total voltage supplied to the electrons by the battery (Figure 9.5). The sum of the voltages lost on the loads equals the total voltage supplied by the batter y.
Did You Know?
When Edison was designing his light bulb, he tried more than 1600 materials for the filament. Some of these materials included thread, fishing line, coconut fibre, bamboo, and the hair from a beard. Edison finally
chose carbonized cotton for the filament.
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Figure 9.5 Each load in a series circuit loses a portion of the total voltage.
In an electric circuit, the electrons repel each other with the same action-at-a-distance force. Therefore, most of the electrons flowing in a circuit will remain fairly evenly spaced apart. Since there is only one path for the electrons to travel in the series circuit, the current in each part of a series circuit is equal (Figure 9.6). This is similar to a garden hose filled with water. The amount of water entering the garden hose must be the same as the amount of water leaving the same hose. All along the hose, therefore, the “current” of water is the same.
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Figure 9.6
The current is the same throughout a series circuit.
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Chapter 9 Circuits are designed to control the transfer of electrical energy. • MHR 309
Suggested Activity
Find Out Activity 9-1D on page 314