Chapter 8 Electricity - Components Flashcards
What is an LDR
Light dependent Resistor - components that have high resistivity in the darkness but low in the light.
What is a thermistor
use
Components that have high resistance when cold but low resistance when hot. Made of semiconductor materials
electrical thermometeres, fire alarm, thermostats
What is a rheostat
use
Variable resistor - Used to vary the current.
used in hi-fi equipment for volume control
What is an LED
what are the colours and what are they used for
Light Emitting Diode - Diode that gives off light when current passes through it
Red, Blue, Green - Indicators on electrical equipment
Arrays of white - source of light in low energy bulbs and torches
How does a reed switch work
use
Operated by a magnetic field
burglar alarms
What is a diode
A component that only allows electricity to flow in one direction
What is forward and reverse bias
what happens with each
Forward and reverse bias are orientations of the diode, which direction it points
When the diode is in forward bias, there is extremely low resistance. Arrow head of the diode points in the same direction as the conventional current
When diode is in reverse bias, there is extremely high resistance. The arrow head points in the opposite direction as conventional current and the current is blocked.
What is a diode also known as
why is it known as this
Aka: Rectifiers
Performs the task of rectification - doesn’t let the backwards parts of the AC current from flowing. Current only flows in one direction.
What is a potential divider
An arrangement that delivers only a proportion of voltage from the battery.
What is an RCD
Residual Current Device - Compares the current in the live and neutral wires. If there is a difference the current is probably flowing to the earth because someone may be touching the exposed wire. This difference triggers the current to shut off before damage is done.
what is the purpose of split ring commutator
keeps coil rotating (in the same direction)
by changing direction of current (in the coil)
every half cycle/180 degrees
