Ohm’s LawOhm’s Law

Would this work?Would this work?

1 2

50%50%

1.1. YesYes

2.2. NoNo

Would this work?Would this work?

1 2

50%50%

1.1. YesYes

2.2. NoNo

Would this work?Would this work?

1 2

50%50%

1.1. YesYes

2.2. NoNo

Parts of a circuit (review)Parts of a circuit (review)

Voltage (V):

Current (I):

Resistance (R):

Human circuits activity #1Human circuits activity #1

In your lab groups, build a HUMAN circuit In your lab groups, build a HUMAN circuit that includes the following:that includes the following: Battery (power source)Battery (power source) 3 Light bulbs in SERIES3 Light bulbs in SERIES

Human circuits activity #2Human circuits activity #2

In your lab groups, build a HUMAN circuit In your lab groups, build a HUMAN circuit that includes the following:that includes the following: Battery (power source)Battery (power source) 3 Light bulbs in PARALLEL3 Light bulbs in PARALLEL

Human circuits activity #3Human circuits activity #3

In your lab groups, build a HUMAN circuit In your lab groups, build a HUMAN circuit that includes the following:that includes the following: Battery (power source)Battery (power source) Light bulbLight bulb Ammeter (to measure current)Ammeter (to measure current) Voltmeter (to measure voltage)Voltmeter (to measure voltage)

Debrief activity: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 If the voltage is increased but the resistance stays the same, the resistance stays the same, what happens to the current?what happens to the current?

1.1. It increasesIt increases

2.2. It decreasesIt decreases

3.3. It stays the sameIt stays the same

Current is directly proportional to voltage

If the resistance is increased but If the resistance is increased but the voltage remains the same, the voltage remains the same, what happens to the current?what happens to the current?

1.1. It increasesIt increases

2.2. It decreasesIt decreases

3.3. It stays the sameIt stays the same

Current is inversely proportional to resistance

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

Ohm’s LawOhm’s Law

Voltage = Current x Resistance Voltage = Current x Resistance

V = IRV = IRVoltage: Voltage: measured in measured in Volts (V)Volts (V)

Current: measured Current: measured in Amps (A)in Amps (A)

Resistance: Resistance: measured in measured in Ohms (Ohms (Ω)Ω)

Practice ProblemPractice Problem

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

Ohm’s Law LabOhm’s Law Lab

Part 1:Part 1:

Part 2: Part 2:

What to do when I finish?What to do when I finish?

1.) Tidy up lab station and turn in lab to 1.) Tidy up lab station and turn in lab to group foldergroup folder

2.) Go to the PHET website and build 2.) Go to the PHET website and build various circuits (your choice). You must various circuits (your choice). You must measure current, voltage, and resistance for measure current, voltage, and resistance for each circuit. Draw a circuit diagram and each circuit. Draw a circuit diagram and record current, voltage and current.record current, voltage and current.

What would the effect be on a person if What would the effect be on a person if they stuck their finger into a regular wall they stuck their finger into a regular wall outlet that supplies 120V (don’t try this at outlet that supplies 120V (don’t try this at

home) with completely dry skin home) with completely dry skin (R=100,000ohms)?(R=100,000ohms)?

1 2 3 4

25% 25%25%25%

1.1. 12,000,000 Amps12,000,000 Amps

2.2. 8333 Amps8333 Amps

3.3. 0.0012 Amps0.0012 Amps

4.4. No currentNo current

What would the effect be on a person if What would the effect be on a person if they stuck their finger into a regular wall they stuck their finger into a regular wall outlet (again don’t try this at home) after outlet (again don’t try this at home) after

sitting in a bathtub full of salt water sitting in a bathtub full of salt water (R=100ohms)?(R=100ohms)?

1 2 3 4

25% 25%25%25%

1.1. 12,000 Amps12,000 Amps

2.2. 1.2 Amps1.2 Amps

3.3. 0.83 Amps0.83 Amps

4.4. No currentNo current