Transcript Slide 1 - MrSimonPorter

Electric symbols
Cell and battery of cells
Lamp
Switch
Ammeter
Voltmeter
Resistor
Variable resistor (rheostat)
Bell/buzzer
Thermistor
• Resistance decreases with increasing
temperature
Resistance
Temp
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