Electric symbols. Cell and battery of cells Lamp.
-
Upload
reynard-richardson -
Category
Documents
-
view
220 -
download
0
description
Transcript of Electric symbols. Cell and battery of cells Lamp.
Electric symbols
Cell and battery of cells
Lamp
Switch
Voltmeter
Resistor
Variable resistor (rheostat)
Bell/buzzer
Thermistor
• Resistance decreases with increasing temperature
Temp
Resistance
Light-dependent resistor (LDR)
• High resistance in the dark but a low resistance in light
Diode
• Allows current to flow in one direction only (from + to – in the direction of the “arrow)
Captain Jack Sparrow smoking a cigar
Two cowboys on a tandem
Two fried eggs in a frying pan
3 wizards looking down a well
• ac/dc• Insulation and double insulation• Earthing, fuses and circuit breakers
Brainiac – Cattle fence
Gather round!
Alternating current
• Current changes direction 50 times a second.
Fuse
• Thin piece of wire which melts if the current is too high
• If a fault develops, this thin piece of wire melts if the current is too high
• Circuit breakers are sometimes used instead
Earth wire
• Connects metal body of appliance to earth• If a live wire comes loose, current flows to
earth and blows the fuse
Double insulation
• Some appliances have no earth wire because they have a plastic outer case
• The plastic case acts as an extra layer of insulation around the wires
Reading!
• Read carefully pages 192-195• Answer the questions on both pages• Finish for homework due Tuesday 13th
January