1. Physics 3 Electricity and Magnetism
Charges in Motion!
Physics 3
Electricity and Magnetism

2. What is electric potential energy?
Energy due to an object’s charge
Which one has more potential to move, A or B?
A B

3. What is Electric Potential Difference or Voltage?
The push of the current
Symbol is V
Measured in Volts
Birds can sit on high potential wires without getting electrocuted? Why???
Voltage in US: 120v
Voltage in Europe: 240v
Can we use our appliances over in Europe???

4. What is electric current?
The flow of the electrons
Symbol is I
Measured in amperes (amps)
See chart for the effects of various current on the body
Purpose of defibulator: use electricity to jump start the heart. Why do they say clear before the shock is delivered?

5. What is electrical resistance?
The fight of the flow of electrons
Symbol is R
Measured in ohms
Depends on temperature, length, material, and thickness of wire

6. Ohms Law V=I x R Voltage = Current x Resistance I=V / R
Current= Voltage divided by Resistance
R=V / I
Resistance= Voltage divided by Current

7. What is Power?
The conversion of electrical energy into some other form of energy
Symbol is P
Measured in watts
P= I x V
Power = Current x Voltage

8. Practice 1
What is the effect of touching a 24 volt battery assuming your body is dry and has a resistance of 100,000 ohms?
I= V / R
I= 24 / 100,000 = amps
Will this kill you????

9. Practice 2
What would be the effect of touching a 24 volt battery assuming your skin is moist and has a resistance of 1000 ohms?
I= V / R
I= 24 / 1000 = amps
What effect will this have on your body?

10. Practice 3
What is the voltage for a current of amps and a resistance of 15,000 ohms?
V = I x R = x 15,000 =
V= 75volts

11. Practice 4
A flashlight bulb uses 0.10amps and has a resistance of 30 ohms. How many volts does the light bulb supply?
V= I x R = 0.10 x 30 = 3volts

12. Practice 5
How many amps are used to run a blow dryer on a 110 volt circuit with a resistance of 100 ohms?
I = V / R = 110 / 100 = 1.1amps