Electricity And Electronics Flashcards
(13 cards)
What colour is the neutral cable
Blue
What colour is the live cable
Brown
What colour is the earth cable
Green or yellow
How do you find the number of kilowatt hours used
Multiply the number of kilowatts by the number of hours
How do you find the cost of electricity
Kilowatt hours multiplied by the price per kilowatt hour
What is a diode
A device which allows current to flow in only one direction
When is a diode forward biased
When the cathode is connected to the negative terminal and the anode is connected to the positive terminal
When is a diode reverse biased
When the cathode is connected to the positive terminal and the anode to the negative
Current can not flow
What is a rectifier
A device that changes ac to dc
What does an led require
A resistor in series to limit the current
Must be forward biased
What are LEDs used in
Indicator lamps
Displays on clocks
What is an LDR
Light dependent resistor
A variable resistor whose resistance decreases as more light falls on it
What are LDRs used in
Street lamps
Burglar alarms
