1. Electrical Current
Mr. Fleming

2. Expected Performances
D4. Explain the relationship among voltage, current and resistance in a simple series circuit.

3. Essential Question
What are the factors that affect how electrons move along a wire?

4. Two types of electricity
Static electricity: electricity involving a build-up of stationary charges.
Current electricity: electricity involving the flow of e- through a material.

6. Ohm’s Law
Voltage, current and resistance are all related to each other by a formula called Ohm’s Law, developed by George Simon Ohm in 1827.
Current = Volts/ Resistance
I= V/R

8. Current Current: rate at which electrons move past a point in a wire.
Measured by using amperes or amps (A)

9. Voltage
Voltage: the difference in electrical potential between two points.
Measured by using Volts (V)
Voltage provides the force or push that moves electrons through a wire.
An increase in voltage causes an increase in electron flow.

10. Resistance
Resistance - opposition of a substance to a flow of electrons.
Measured by using Ohms (Ω)
The higher the resistance; the lower the current.

11. Factors Affecting Resistance
Material
Thickness of a wire
Length of a wire
Temperature

12. Power Equation
Power is a function of Voltage and current expressed by the equation.
P = I x V

13. Power
Power: The rate at which energy is transferred or used in an electrical circuit.
Measured by using Watts (W)

15. Steps to solving Word Problems:
Read the problem
2. List all known values with their units
3. Write out equation with unknown isolated
4. Plug in #’s with units
5. Solve, give answer with PROPER UNIT!

16. Formulas Current = Volts/ Resistance I= V/R
Power is a function of Voltage and current expressed by the equation.
P = I x V

17. Sample Problem #1
What is the current passing through a 3 W resistance that is connected to a volt battery?

18. Sample Problem #1
12 volts/3 ohms= 4 amps

19. Sample Problem #2
A 30 amp current is passing through a 4 W resistor, what is the voltage in the circuit?

20. Sample Problem #2
30 amps x 4 ohms= 120 volts

21. Sample Problem # 3
A 6 v battery pushes electrons through a circuit with a current of 0.3 amps, what is the resistance of this circuit?

22. Sample Problem # 3
6 volts/ 0.30 amps= 20 ohms

23. Sample Problem #4
A 12 v battery causes a 0.3 amp current to pass through a bulb. A) What is the bulb’s power usage? B) What is the resistance of the bulb?

24. Sample Problem #4 12 volts x 0.3 amps= 3.6 watts
12 volts/ 0.3 amps= 40 ohms

25. Sample Problem #5
A.) How much current passes through a 40 W bulb attached to a 120 v power source? B.) What is the resistance of the bulb?

26. Sample Problem #5 40 watts/ 120 volts= 0.33 amps
120 volts/0.33 amps= 363 ohms

27. Sample Problem #6
A. A 100 W bulb has a 0.2 amp current passing through it, what is the voltage of the power source? B. What is the resistance of the bulb?

28. Sample Problem #6 100 watts/ 0.20 amps= 500 volts
500 volts/0.20 amps= 2500 ohms

29. Electrical Current Recall
Name 2 factors or things that affect current? Voltage and Resistance How are resistance and current related to each other? Amps= Volts/ Ohms Ohms= Volts/Amps