Chapter 13.7: Resistance
Learning Goals: Understand the factors that affect resistance.Success Criteria: You can describe factors that affect resistance and how the affect resistance.
Definition: Resistance is the ability of a material to oppose the flow of electrons. Measured in units of Ohms, Ω
Do conductors or insulators have higher resistance? Answer: insulators!
Here are some analogies for resistors.
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| Resistors behave like a small pipe. They restrict the flow of electrons. |
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| A regular slide has low resistance. |
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| A slide made of sandpaper has very high resistance! |
Factors that affect resistance
- material (conductors have low resistance)
- cross sectional area (thick wires have low resistance)
- length (shorter wires have low resistance)
- temperature (colder things have lower resistance)
Superconductors have zero resistance. They do amazing things like levitate above magnets. Watch this:
Resistors in Circuits
Resistors can be added to circuits to increase the resistance.
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| The symbol for resistors when you draw circuit diagrams. |
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| Here's what they look like in real life. |
Increasing resistance decreases the current.
Homework questions: P. 566 # 3, 4, 5, 6
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