1. Physics Electric Circuits

2. –V = I x R –Power (Watts) = I 2 x R = I x V –Series and parallel circuits

3. Today’s Agenda Unit Overview Unit Overview Begin Static Electricity Begin Static Electricity –Electric charges –Electric forces –Fields

4. Physics Electric and Magnetic Phenomena

5. California State Standards Physics: Electric and Magnetic Phenomena 5. Electric and magnetic phenomena are related and have many practical applications. As a basis for understanding this concept: a. Students know how to predict the voltage or current in simple direct current (DC) electric circuits constructed from batteries, wires, resistors, and capacitors. b. Students know how to solve problems involving Ohm’s law.

6. California State Standards c. Students know any resistive element in a DC circuit dissipates energy, which heats the resistor. Students can calculate the power (rate of energy dissipation) in any resistive circuit element by using the formula Power = IR (potential difference) ×I (current) = I 2 R. d. Students know the properties of transistors and the role of transistors in electric circuits. e. Students know charged particles are sources of electric fields and are subject to the forces of the electric fields from other charges.

7. California State Standards f. Students know magnetic materials and electric currents (moving electric charges) are sources of magnetic fields and are subject to forces arising from the magnetic fields of other sources. g. Students know how to determine the direction of a magnetic field produced by a current flowing in a straight wire or in a coil. h. Students know changing magnetic fields produce electric fields, thereby inducing currents in nearby conductors. i. Students know plasmas, the fourth state of matter, contain ions or free electrons or both and conduct electricity.

8. California State Standards j.* Students know electric and magnetic fields contain energy and act as vector force fields. k.* Students know the force on a charged particle in an electric field is qE, where E is the electric field at the position of the particle and q is the charge of the particle. l.* Students know how to calculate the electric field resulting from a point charge. m.* Students know static electric fields have as their source some arrangement of electric charges.

9. California State Standards n.* Students know the magnitude of the force on a moving particle (with charge q) in a magnetic field is qvB sin(a), where a is the angle between v and B (v and B are the magnitudes of vectors v and B, respectively), and students use the right-hand rule to find the direction of this force. o.* Students know how to apply the concepts of electrical and gravitational potential energy to solve problems involving conservation of energy.

11. Electric Circuits

12. Light Bulb

13. Some Electrical Symbols BatteryLampSwitch(open)Wire+CapacitororResistorDiode +

14. Schematics

15. Switches Break The Circuit

16. Series Circuit

17. Parallel Circuit

18. Amps Kill! Current in amperes Effect 0.0010.0050.0100.0150.070 Can be felt Painful Involuntary muscle contractions (spasms) Loss of muscle control If through the heart, serious disruption; probably fatal if current lasts for more than one second Source: Conceptual Physics, page 537

19. Ohm’s Law V = IRI = V/RR = V/I V = IRI = V/RR = V/I Voltage = Current x Resistance Voltage = Current x Resistance Current = Voltage/Resistance Current = Voltage/Resistance Resistance = Voltage/Current Resistance = Voltage/Current V = Voltage (Volts) V V = Voltage (Volts) V I = Current (Amperes, amps) A I = Current (Amperes, amps) A R = Resistance (Ohms) Ω R = Resistance (Ohms) Ω

20. Resistance in a Series Circuit R (total) = R 1 + R 2 + R 3 + … R (total) = R 1 + R 2 + R 3 + …+ R1R1 R2R2 R3R3

21. Resistance in a Parallel Circuit (1) R (total) = (R 1 x R 2 ) / (R 1 + R 2 ) R (total) = (R 1 x R 2 ) / (R 1 + R 2 ) 1/R (total) = 1/R 1 + 1/R 2 1/R (total) = 1/R 1 + 1/R 2 + R1R1 R2R2

22. Resistance in a Parallel Circuit (2) 1/R (total) = 1/R 1 + 1/R 2 1/R (total) = 1/R 1 + 1/R 2 R (total) = (R 1 x R 2 ) / (R 1 + R 2 ) R (total) = (R 1 x R 2 ) / (R 1 + R 2 )+ R1R1 R2R2

23. Power Power (Watts) = I 2 x R = I x V Power (Watts) = I 2 x R = I x V Power = Current x Voltage Power = Current x Voltage

24. AC-to-DC Converter (Rectifier)