1. Current and Simple Circuits Voltage Resistance Safety
Electricity
Current and Simple Circuits
Voltage
Resistance
Safety

2. Current Flow of charge Amount of charge flowing per unit time Equation
Measured in amperes, A
Amount of charge
Time taken Q t

3. Circuit and Symbols A path where electrons can flow
Three important parts
Source of energy
Battery
Power Supply
Conducting Path
Electrical wires
Resistor
Fixed resistor
Lamp
Switch
                              

4. Voltage Energy per unit of a charge Equation Unit: Volt, V
“driving force” that pushes charges around the circuit
Two basic types
emf (electromotive force)
pd (potential difference)
Energy
Charge

5. Resistance Proportional to length of conductor
Inversely proportional to thickness (or cross-sectional area) of conductor

6. Ohm’s Law
Current in a resistor is proportional to voltage provided temperature is constant
Equation
Resistance =
Voltage
Current

7. Power Energy per unit time Equation Unit: Power =
Joules per second, Js-1
Watt, W
Energy
Time

8. Types of Circuits Series Circuit Parallel Circuit
One path for charges to flow
Parallel Circuit
More than one loop or path

9. Current
Itotal = I1 = I2 = In
Itotal = I1 + I2 + In

10. Voltage
Vtotal = V1 + V2 + Vn
Vtotal = V1 = V2 = Vn

11. Resistance = 1 1 1 1 + +
Rtotal = R1 + R2 + Rn
Rtotal R1 R2 Rn

12. Measuring Current and Voltage
Voltmeter
Connected parallel to element being measured
Current
Ammeter
Connected in series to element being measured
Ohmmeter
Measures resistance

13. Safety Fuse Circuit Breaker
Used to regulate the amount of current in the circuit
If the current is too high, it opens the circuit
Circuit Breaker