180 likes | 332 Views
Ohm’s Law. Would this work?. Yes No. Would this work?. Yes No. Would this work?. Yes No. Parts of a circuit (review). Voltage (V): Current (I): Resistance (R):. Human circuits activity #1. In your lab groups, build a HUMAN circuit that includes the following:
E N D
Would this work? • Yes • No
Would this work? • Yes • No
Would this work? • Yes • No
Parts of a circuit (review) Voltage (V): Current (I): Resistance (R):
Human circuits activity #1 • In your lab groups, build a HUMAN circuit that includes the following: • Battery (power source) • 3 Light bulbs in SERIES
Human circuits activity #2 • In your lab groups, build a HUMAN circuit that includes the following: • Battery (power source) • 3 Light bulbs in PARALLEL
Human circuits activity #3 • In your lab groups, build a HUMAN circuit that includes the following: • Battery (power source) • Light bulb • Ammeter (to measure current) • Voltmeter (to measure voltage)
Debrief activity: Measuring voltage: Voltmeter must be placed in PARALLEL with resistor Measuring current: Ammeter must be placed in SERIES
If the voltage is increased but the resistance stays the same, what happens to the current? • It increases • It decreases • It stays the same Current is directly proportional to voltage
If the resistance is increased but the voltage remains the same, what happens to the current? • It increases • It decreases • It stays the same Current is inversely proportional to resistance
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).
Ohm’s Law Voltage = Current x Resistance V = IR Resistance: measured in Ohms (Ω) Voltage: measured in Volts (V) Current: measured in Amps (A)
Practice Problem A lightbulb with resistance of 100 is plugged into a 120 V outlet. What is the current flowing through the bulb?
Ohm’s Law Lab • Part 1: • Part 2:
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.
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)? • 12,000,000 Amps • 8333 Amps • 0.0012 Amps • No current
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)? • 12,000 Amps • 1.2 Amps • 0.83 Amps • No current