Electrical Engineering

Electrical Engineering Covers two main areas: - Electricity - Electronics

All appliances and electrical devices depend on electrical circuits

Electrical component are made with a particular

type of material: - Semiconductor (silicon)- Conductors (metals & alloys)

Symbols for circuit components

Direct current & Alternating current Direct current (DC): is an

electric current in which the electrons are continuously moving in the same direction.

Alternating current (AC): is an electrical current in which the electrons move back and forth in a regular pattern

Electrical Function Is the role that a component plays in

the control or transformation of electric current.

Power supply: is the electrical function preformed by any component that can generate or provide an electric current in a circuit

Types of power supplies Battery: Transforms

chemical energy into electrical energy

Advantages: portable, many appliances run on batteries

Disadvantages: batteries must be

replaced, contaminate the environment around the landfill by leaking heavy metals

Electrical outlet: contains contacts and is permanently connected to an electrical network

Advantages: stable and long lasting power supply

Disadvantages: hydroelectric dams cause flooding of vast areas of land. Appliances cannot be moved far from the wall outlet

Photovoltaic cell: (solar cell) electronic device that generates an electrical current when exposed to light.

Advantages: portable, do not produce green house gases, have a lifespan of 20 to 30 years.

Disadvantages: Depends on sunny conditions. Much more expensive to install than other sources of power.

Conduction, insulation & protection Conduction:

When a component can transmit electric current from one part of a circuit to another

Examples of conductors: copper, gold, etc...

Insulation :

When a component prevents an electric current from flowing.

Examples of insulators: ceramic, rubber, plastic

Protection: Cut current flow in the even of a power surge Fuses

A filament melts/breaks if current exceeds a certain level

Breakers

A strip becomes hot and bends if current exceeds a certain level. A switch is thrown to restore circuit operation

Open/closed circuit

Closed circuit: electric current lows in a loop

Open circuit: electric current cannot flow in a loop

In class work P. 479

#1,2,3,4,5,6,7,8,9,10,11,13,14

Transformation of energy The transformation of energy is the

electrical function performed by any component that can convert electrical energy into another form of energy

Forms of energy Chemical

Thermal

Mechanical

Radiation

Examples of electrical components used to transform

electrical energy Incandescent light

bulbs (luminous energy)

Heating elements (thermal energy)

Piezoelectric crystals (mechanical energy)

Electromagnets (magnetic energy)