Night Light Circuit Components Flashcards
What is an LDR also called?
A light sensor
An LDR stands for what?
Light Dependant Resistor
What component is an LDR?
A input component (sensor)
What does an LDR do?
It converts brightness (light) to resistance
What is LDR made from?
Cadmium sulphide (CdS)
What does the resistance in an LDR do?
It varies/ decreases as the brightness of light falling on the LDR increases
What is an LDR’s darkness maximum resistance and its very bright light minimum resistance?
Darkness: about 1m (omega symbol)
Very bright light: about 100 (omega symbol)
Transistors behave like what?
An electronic switch
What are the three legs of a transistor called?
Base, collector and emitter
What does LED stand for?
Light Emitting Diode
When do LED’s emit light?
When an electronic current passes through them
Fill in the blank-
LEDs must be connected the right way round, the diagram may be labelled ____ or _____ for anode and ____ or ____for cathode
Labelled a or + for anode and k or - for cathode
Is cathode negative or positive?
Negative
How can you tell what leg is the cathode?
There may be a slight flat on the body of round LEDs
Also, if you can see inside the LED the cathode is the larger electrode ( this is not an official method)
How can LEDs become damaged?
By heat from soldering but the risk is small unless you go slowly
