1. Ohm’s Law

2. Would this work? 1. Yes 2. No

3. Would this work? 1. Yes 2. No

4. Would this work? 1. Yes 2. No

5. Parts of a circuit (review) Voltage (V): Current (I): Resistance (R):

6. Human circuits activity #1  In your lab groups, build a HUMAN circuit that includes the following: Battery (power source) Battery (power source) 3 Light bulbs in SERIES 3 Light bulbs in SERIES

7. Human circuits activity #2  In your lab groups, build a HUMAN circuit that includes the following: Battery (power source) Battery (power source) 3 Light bulbs in PARALLEL 3 Light bulbs in PARALLEL

8. Human circuits activity #3  In your lab groups, build a HUMAN circuit that includes the following: Battery (power source) Battery (power source) Light bulb Light bulb Ammeter (to measure current) Ammeter (to measure current) Voltmeter (to measure voltage) Voltmeter (to measure voltage)

9. Debrief activity: Measuring voltage: Voltmeter must be placed in PARALLEL with resistor Measuring current: Ammeter must be placed in SERIES

10. If the voltage is increased but the resistance stays the same, what happens to the current? 1. It increases 2. It decreases 3. It stays the same Current is directly proportional to voltage

11. If the resistance is increased but the voltage remains the same, what happens to the current? 1. It increases 2. It decreases 3. It stays the same Current is inversely proportional to resistance

12. So... Ohm's law states that the electrical current (I) flowing in an circuit is proportional to the voltage (V) and inversely proportional to the resistance (R).

13. Ohm’s Law Voltage = Current x Resistance V = IR Voltage: measured in Volts (V) Current: measured in Amps (A) Resistance: measured in Ohms (Ω)

14. Practice Problem A lightbulb with resistance of 100  is plugged into a 120 V outlet. What is the current flowing through the bulb? A lightbulb with resistance of 100  is plugged into a 120 V outlet. What is the current flowing through the bulb?

15. Ohm’s Law Lab  Part 1:  Part 2:

16. What to do when I finish? 1.) Tidy up lab station and turn in lab to group folder 2.) Go to the PHET website and build various circuits (your choice). You must measure current, voltage, and resistance for each circuit. Draw a circuit diagram and record current, voltage and current.

17. What would the effect be on a person if they stuck their finger into a regular wall outlet that supplies 120V (don’t try this at home) with completely dry skin (R=100,000ohms)? 1. 12,000,000 Amps 2. 8333 Amps 3. 0.0012 Amps 4. No current

18. What would the effect be on a person if they stuck their finger into a regular wall outlet (again don’t try this at home) after sitting in a bathtub full of salt water (R=100ohms)? 1. 12,000 Amps 2. 1.2 Amps 3. 0.83 Amps 4. No current