electricity Flashcards
the equivelant unit for volts
joules per columb
what is ohms law
ohms law is a relationship that exists between voltage, current and resistance in some materials
factors affecting the resistance of a wire
length - longer wires have a higher resistance
thickness - thicker wires have a lower resistance
temperature - higher temperature wires have a higher resistance
what is a potential divider
a potential divider is a series circuit that usually contains two resistors and is used to split or divide a supply voltage. The larger resistor in the circuit takes a larger share of the supply voltage
what is an input device
input devices change some form of energy e.g light, sound, heat into electrical energy. For example a microphone
what is an output device
output devices convert electrical energy into another form e.g sound, light, kinetic. For example a lamp
what is the power of an appliance?
the power of an appliance is the energy it consumes per second. Appliances that produce a lot of heat have high power ratings
what is power measured in?
What is charge measured in?
What is current measured in?
What is voltage measured in?
What is resistance measured in?
What is energy measured in?
What is time measured in?
power - watts
charge - columbs
current - amps
voltage - volts
resistance - ohms
energy - joules
time - seconds
what is the effect of temperature on resistance?
What is the effect of light level on resistance?
Temperature Up Resistance Down
Light Up Resistance Down
what is an alternative unit for power?
joules per second js-1
what is a thermistor ?
a thermistor is a resistor which changes its resistnce in response to a change in temperature and light level respectively
what is a transistor?
a transistor is an automatic electronic switch. It can be used to switch on a component when the voltage across 2 of its terminals exceeds a certain level.
what is an autoswitching sensing circuit
these are circuits that use potential dividers along with ldrs, thermistors and transistors to automatically switch circuits on and off under certain environmental conditions
what is a fuse
a fuse is a very thin piece of wire enclosed in a glass or ceramic tube which protects the flex of an appliance and the appliance itself from overheating due to high current
