Electricity Flashcards
What is an electric current?
A movement of charges around a circuit
What is the voltage of a power supply a measure of?
The energy given to the charges in a circuit
State the series current rule?
The current is the same at all points
state the series voltage rule?
The voltage across the components add up to the power supply voltage
state the parallel current rule?
The current through the branches add up to the current drawn from the supply
State the parallel voltage rule?
the voltage across each component is the same and equal to the supply voltage
What happens to the resistance of a conductor when it is heated?
increases
What does the power rating mean?
The rate at which an appliance transforms electrical energy into other forms
An LED will only light when connected the right way round, what way is this?
The arrow must point from + to -
The resistance of a thermistor changes with what?
Temperature
When does the resistance of a LDR decrease?
When more light reaches it
What is a relay device?
A device which allows a small current in one circuit to switch on a larger current in another circuit
Describe a d.c current?
Current has constant direction and value does not change with time?
Describe an a.c current?
Current changes direction and value with time
What graph does an oscilloscope display?
Voltage against time
Describe mains supply?
a.c current
Frequency = 50Hz
Quoted value = 230V
Peak value = 325V
The quoted value on an alternating voltage is always what?
Less than its peak volatge
What is a potential divider circuit?
Two resistors connected in series
In a potential divider the power supply voltage is what?
Shared between the two resistors.
The largest resistor in the potential diver gets the what?
Largest share of the voltage
Potential divider circuits can be used to?
Set and control voltages in electronic circuits.
