Transcript File
CONDUCTION, INSULATION AND PROTECTION CONDUCTION Energy (eg. Electrical) transfer from one material to another by direct contact. Conductors are materials that allow transfer to happen. Examples of good conductors are copper, aluminum, silver and optical fibres. Transition metals are good conductors of electricity and heat. PRINTED CIRCUITS ELECTRICAL CIRCUIT PRINTED ON A THIN RIGID BOARD ONE METHOD HAS BOARDS COVERED WITH COPPER, THE CIRCUIT IS THEN ETCHED INTO THE COPPER AND THEN THE REST OF THE COPPER IS DISSOLVED AWAY LEAVING JUST THE CIRCUIT; ELECTRIC AND ELECTRONIC COMPONENTS ARE THEN SOLDERED INTO HOLES DRILLED INTO THE BOARDS MASS MANUFACTURING OF CIRCUIT BOARDS VIDEO Printed Circuit Board Video There are many devices that use circuit boards: Cell phones, MP3 Players, DVD players, TV’s, Computers, and the list can go on…. INSULATION THE ELECTRICAL FUNCTION PERFORMED BY A COMPONENT TO PREVENT THE FLOW OF AN ELECTRIC CURRENT PREVENT INJURY AS WELL AS SHORT CIRCUITS CERAMIC AND PLASTIC ARE GOOD INSULATORS THAT CAN BE WRAPPED AROUND A WIRE, OR USED TO CONTAIN ELECTRIC FLOW. PROTECTION FUSES AND CIRCUIT BREAKERS ARE EXAMPLES OF PROTECTION PROTECTION IS A COMPONENT THAT STOPS THE FLOW OF CURRENT IN THE EVENT OF A POWER SURGE FUSES • Fuses regulate the amount of amps that go through a circuit. • When a circuit is performing normally, the electrons will flow through the filament of a fuse. • Filaments can be found in many different fuses, light bulbs, diodes and many other electrical elements. • If the current intensity is to high the filament will either melt, or break into two pieces. • At this point the fuse will need to be replaced. Breaker • It is a protective device that can be reset as many times necessary, thus it is better than a fuse as a fuse needs to be replaced every time the filament breaks. • Electrons flow through a bimetallic strip. If the current intensity gets to high, the strip heats up and bends. • The bending of this strip makes the breaker shut off and snap over to the off position. • When this happens you can go to your breaker panel and reset the breaker switch. RESISTANCE IS MEASUREDC IN OHMS ELECTRICAL RESISTANCE RESISTORS LIMIT THE FLOW OF ELECTRONS THROUGH AN ELECTRICAL CIRCUIT READING A RESISTOR ON 4 BANDS RESISTORS- THE 1ST TWO BANDS TELL YOU THE FIRST TWO DIGITS OF RESISTANCE (ex. RED=2; BLUE=6) THE NEXT BAND TELLS YOU WHAT TO MULTIPLY THOSE NUMBERS BY (ex. RED=100) LAST BAND IS TOLERANCE FACTOR (EX. GOLD= ±5%) THEREFORE A RESISTOR WITH RED, BLUE, RED, GOLD WOULD HAVE RESISTANCE OF 2600 ohms ±5% Colour coding on resistors Resistors are coated with ceramic. They have color coded bands to indicate resistance 1st & 2nd band first two digits of resistance 3rd band Number of zeros to add after the first two numbers. 2nd Resistor 3rd 1st Example: The resistor on the right has the following value. First colour is red, thus first digit is 2 and the second colour is orange, thus the second digit is 3 = 23 The third colour is yellow, and this digit is 4 we therefore find 104 = 10000 This resistance would be 10000 X 23 = 230 000 W Black 0 Brown 1 Red 2 Orange 3 Yellow 4 Green 5 Blue 6 Violet 7 Gray 8 White 9