1. Electrical Resistance
Electrons like any other moving body follow the path of least resistance.
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2. Which road would you want to travel on?
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3. Which road would you want to travel on?
Electrons in a circuit are like cars on a road – what happens when electrons encounter a traffic problem?
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4. Resistance
“Electrical Friction” Opposition to the flow of moving electrical charges
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5. “Resistance is Futile”?
If resistance is “electrical friction”, what benefits could resistance provide when making a circuit?
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6. Is resistance in a wire always bad?
Problem of the Day
Is resistance in a wire always bad?
Resistance in a light bulb
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7. Is resistance futile in a lightbulb?
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9. Symbol for Resistance R
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10. Unit of Measurement
ohm
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11. What kind of wires would increase resistance in a circuit?
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12. Resistance slows down moving electrons
Resistance slows down moving electrons. When electrons slow down they convert electrical energy into light, heat and sound What impacts resistance in a wire?
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13. 4 things that can change resistance
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14. The resistance in a wire depends on:
A metals structural resistance to electron flow
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15. The resistance in a wire depends on:
1. The type of metal in the wire
Which metals have low resistance?
Which metals have high resistance?
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16. The resistance in a wire depends on:
1. The type of metal in the wire
Which metals have low resistance?
Silver and Copper
Which metals have high resistance?
Nichrome and Tungsten
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17. The resistance in a wire depends on:
Length of the wire
The shorter the wire the less resistance there is
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18. The resistance in a wire depends on:
Thickness (Cross Sectional Area) of the wire
The wider the wire the less resistance there is
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19. The resistance in a wire depends on:
Temperature:
The colder it is the less resistance there is
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20. Why are different wires used with different appliances?
Problem of the Day
Why are different wires used with different appliances?
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22. Ohm’s Law V= I x R Voltage (Volts)=
Current (Amps) times Resistance (ohms)
electric current is directly proportional to voltage and inversely proportional to resistance
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23. Ohm’s Law Practice Problem
How much current is in a circuit with a 9 V battery and a light bulb with a resistance of 3 ohms?
Current (A)
Voltage (V)
Resistance (Ω )
Formula
Answer with Unit
Looking for this
I= ? 9V 3Ω
I = (V/R)
V divided by R
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24. Ohm’s Law Practice Problem
How much current is in a circuit with a 9 V battery and a light bulb with a resistance of 3 ohms?
Current (A)
Voltage (V)
Resistance (Ω )
Formula
Answer with Unit
Looking for this
I= ? 9V 3Ω
I = (V/R)
V divided by R 3A
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25. Ohm’s Law Practice Problem
What is the voltage of a circuit with 15 A of current and a toaster with 10 ohms of resistance?
Current (A)
Voltage (V)
Resistance (Ω )
Formula
Answer with Unit
15 A
V= ? 10
V= I R
150 V
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26. OHM’s Law Summary
If Voltage increases, Current _____________ If Resistance increases, Current ____________
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27. Ohm’s Law Summary
If Voltage increases, Current increases More batteries = More current If Resistance increases, Current decreases More load = lower current
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28. Question of the Day
What 4 things affect a circuit to give it more/less resistance?
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29. Question of the Day
What 4 things affect a circuit to give it more/less resistance?
Type of conductor used
Length of wire
Width of wire
Temperature
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30. Question of the Day
What 4 things would produce the most resistance in a circuit?
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31. Question of the Day
What 4 things affect a circuit to give it more/less resistance?
Use Tungsten
Long wire
Thin of wire
Warm Temperature
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