U2 Electricity and Magnetism

What is Electric Current

• The rate of FLOW of electric charges

Measuring Electric Current

• The AMOUNT of CHARGE that passes a location in the wire every second
• It is expressed as AMPERES or amps
• Units are shortened to just (A)

Types of Current

• Two kinds - DIRECT and ALTERNATING
• Direct is abbreviated as (DC)
• Alternating is abbreviated as (AC)

Direct Current

• The electrical charges flow in the SAME direction
• Examples: Batteries, Flashlights, Cars, Cameras

Alternating Current

• Charges repeateldy SHIFT from flowing in one direction to flowing in the reverse direction
• Exmaples: Electrical current from outlets in your home

Factors that Affect Electric Current

• Voltage - the amount of WORK required to move each unit of charge between two points
• Resistance - the OPPOSIYION to the flow of electric charge

Voltage

• Higher the voltage the higher the rate of flow of electric charges
• Units are volts (V)
• Also referred to as ELECTRIC POTENTIAL

Resistance

• Some objects will RESIST the flow of electric charges
• Units are OHMS
• Higher the resistance at same voltage means you will have a lower current

What Affects Electrical Resistance

• 1.Composition of material
• Conductor = LOW resistance
• Insulator = HIGH resistance

What Affects Electrical Resistance

• 2. Thickness
• 3. Length
• 4. Temperature

Untitled Slide

• Thin wire = HIGHER resistance
• long wire = HIGHER resistance
• hot wire = HIGHER resistance

What is Electromagnetism?

• Is a relationship between ELECTRICITY and MAGNETISM
• Results when ELECTRIC currents and MAGNETIC fields interact with each other

To make and Electromagnet

• Wire
• Iron Core
• Battery

Simply wrap the wire (connected to a battery) around the iron core

Strength of Electromagnet

• Strengthen the magnet by adding MORE loops of WIRE around the iron core
• Or add a bigger battery source

Electrical Motors

• Changes ELECTRICAL energy into MECHANCIAL energy

Electromagnetic Induction

• Using a MAGNETIC field to create ELECTRIC current
• Works by MOVING a magnet inside a COIL of WIRE

Transformers

• Use induction to INCREASE or DECREASE the voltage of alternating current

Electric Generators

• Use induction to change MECHANICAL energy to ELECTRICAL energy
• Opposite of an electric motor