Electricity

The Quick Version

Voltage is how much electricity, or push, measured

in Volts (V)

Power is how much electrical energy being delivered in a unit of time, measured in

Watts (W)

Current is the measure of electrical flow and is measured

in amperes or “amps” (A) and its symbol is I.

Resistance slows electricity down as it moves through a

circuit. It has a symbol of R and is measured in Ohms (Ω).

Electricity flows from areas of high volts to areas of low volts.

This is known as potential difference or voltage!

Equations

R=____VI

V=I R

I = ____VR

Equations

P=VI

Electricity and Circuits

Property

• Voltage (V)• Current (I )• Resistance (R)• Power (P)

Units of Measure

• Volts (V)• Amps (A)• Ohms (Ω)• Watts (W)

Electric Circuits• An electric circuit is a network of electrical

components (resistors, transmission lines, electrical sources, switches, etc.) that forms a closed loop and provides a path for electrical energy.

• Circuits have three basic parts:– An energy source that converts non-electrical energy

into electrical energy; examples are batteries and generators.

– An output device that uses electrical energy to do work; examples are motors, lamps, and displays.

– Materials to make a connection to allow electrical energy to flow; examples are wires and cables

Examples of Symbols for Circuit Examples of Symbols for Circuit DiagramsDiagrams

Component Symbol Function of Component

Wire To pass current from one part of a circuit to another

Wires joined A ‘dot’ should be drawn to show where two wires join together.

Battery Supplies electrical energy; the larger terminal is positive (+)

Light Bulb and Socket Converts electrical energy to light energy

Resistor Restricts the flow of current

On-Off Switch Allows current to flow only when it is in the ‘on’ (closed) position

+ -

Light Bulb Resistor

Series CircuitsSeries CircuitsElectrical components connected in series are connected along a single path so the current only has one path to follow.

If one component in a If one component in a series circuit is series circuit is disconnected or fails, the disconnected or fails, the entire circuit is turned off.entire circuit is turned off.

battery

switch

Bulb A

Bulb B

In the circuit to the left, In the circuit to the left, what would happen if what would happen if Bulb B burned out?Bulb B burned out?

If Bulb B burned out there would be no way for the electrical energy to flow. Bulb A

would not light.

Parallel CircuitsParallel Circuits

battery

Bulb A Bulb B Bulb C

Electrical components connected in parallel are connected so that the current has multiple paths that it can take.

If one component in a If one component in a parallel circuit is removed parallel circuit is removed or fails, the other or fails, the other components will still have components will still have an intact path for current an intact path for current and will continue to work.and will continue to work.

Review Activity – CircuitsReview Activity – CircuitsAnswer the questions on the Review Sheet. After you have finished, your Answer the questions on the Review Sheet. After you have finished, your

teacher will help you check your answers using this animation.teacher will help you check your answers using this animation.

Batteries

Switch A Switch B Switch C Switch D

Bulb A Bulb B Bulb C Bulb D

Resistors• A resistor is a component that restricts the flow of

current. • Resistance is measured in ohms. The symbol for the

ohm is (omega).• On a circuit diagram, resistors are represented by

24

THE END!!