1. 4.2.3A Ohm’s Law & Circuit Basics Why Make Electrons Flow Anyway?

2. Ohm’s Law Voltage results in current flow More voltage = more current Resistance opposes current flow More resistance = less current

3. A potential difference of 25.0 volts is supplied to a circuit with 100 ohms of resistance. –How much current flows through this circuit? Example #1 I = V / R I = 25.0 V / 100 Ω I = 0.25 A

4. A current of 2.0 amperes flows through a 10 ohm resistance. –What voltage must be applied to this resistance? Example #2 I = V / R V = IR V = (2.0 A)(10 Ω) V = 20 V

5. A 10 volt battery establishes a current of 5.0 amperes in a circuit. –What is the resistance of this circuit? Example #3 I = V / R R = V / I R = (10 A) / (5.0 A) R = 2.0 Ω

6. What is a circuit? A continuous loop through which current flows from an area of high voltage to a an area of low voltage.

7. Circuit Elements – Voltage Sources batterycell

8. Circuit Elements – Resistances variable resistorfixed resistor lamp

9. Circuit Elements – Switch switch

10. Circuit Elements – Measuring Devices Measures: VOLTAGE Resistance: HIGH Connect to circuit: OUTSIDE voltmeter Measures CURRENT Resistance: LOW Connect to circuit: INSIDE ammeter

11. Proper Use of Meters 5 V 2.5 Ω 0 V 2 A 5 V 0 V 2 A 5 V NEXT

12. End of 4.2.3A