1. Electrical Resistance Activity

2. Curriculum Big Idea: Energy can be transferred between objects and/or can be converted into different forms. Concept: Electricity is the result of converting one form of energy into another and the flow of electrons via a conductor. PA Standard 3.2.P.B4: Explain how stationary and moving particles result in electricity and magnetism. Develop qualitative and quantitative understanding of current, voltage, resistance, and the connections among them. Explain how electrical induction is applied in technology. 3.2.P.B4: Explain how stationary and moving particles result in electricity and magnetism. Develop qualitative and quantitative understanding of current, voltage, resistance, and the connections among them. Explain how electrical induction is applied in technology.3.2.P.B4: Explain how stationary and moving particles result in electricity and magnetism. Develop qualitative and quantitative understanding of current, voltage, resistance, and the connections among them. Explain how electrical induction is applied in technology.

3. Today’s Agenda Opener: Answer the “What Do You Think?” Questions in the Electrical Resistance Activity (see handout). Discuss in small groups and as a class. Go over the homework. For You To Do: Investigate resistance circuits by wiring circuits with nicrome wire (a high resistance wire). Discuss resistance. (Honors) Take notes on Ohm’s Law (Honors) Ohm’s Law Review Problems (see handout) (Honors) Closure: Correct answers to Ohm’s Law Review Problems (Academic) Closure: What is resistance? What is the unit for resistance? (Honors) Take Home Assignment: Physics to Go in the “Resistance” packet. (Academic) Take Home Assignment: Page 560 #4-8 will be checked tomorrow

4. Ohm’s Law Ohm’s Law: The relationship between current, voltage and resistance

5. Current and Voltage Current and Voltage are directly proportional so that when the voltage increases and the resistance stays the same, the current also increases. When the voltage decreases and the resistance stays the same, the current decreases.

6. Current and Resistance Current and resistance are inversely related so that as the resistance increases and the voltage stays the same, the current decreases. When the resistance decreases and the voltage stays the same, the current increases.

7. Current = Voltage Resistance Current – I Voltage – V Resistance – R I (Amperes) = V (Volts) R (ohms: Ω) R (ohms: Ω)

8. Example 1 If a circuit has a voltage drop of 1.5 V and a resistance of 2 ohms, what is the current flowing through the circuit? I = V R I = 1.5V 2 ohms I = 0.75 Amps

9. Example 2 If there are 0.5 Amps of current and a resistance of 3 ohms, what is the voltage? V = I*R V = 0.5 Amps * 3 ohms V = 1.5 Volts

10. Examples If the current is 1 Amp and the voltage is 4 Volts, what is the resistance? R = V I R = 4 Volts 1 Amp 1 Amp R = 4 ohms