1. Ohm’s Law Notes JAN 7

2. Vocabulary current : how quickly the electrons are flowing through the circuit; units: amperes (A) voltage : the electric potential energy that pushes the electrons; units: volts (V) resistance: an effect of the parts of the circuit that slow down the electrons; units: ohms (Ω)

3. Ohm’s Law In any circuit voltage = current ( I ) x resistance

4. Practice Problems. 1. What is voltage if current is 1.5 amperes and resistance is 30 ohms? 2. What is the current flowing through a wire if the resistance is 20 ohms and the voltage is 40 volts? 3. What is a wire’s resistance if a current of 0.5 amperes flows through a wire and the voltage is 50 volts?

5. Electrical Power  For any circuit the Power = voltage x current  Units of Power: Watts

6. How do you pay for Power?  First calculate electric power in watts Then multiply watts by hours, and divide by 1000 to get kilowatts  You pay by the kilowatt-hr

7. Practice problems 4. Your clothes dryer has 220V running into it and a current of about 18A. How much Power does it use? 5. How much energy in kilowatt hours do you pay for if the dryer is used for 1.5hours?