electricity Flashcards
What is electric current
The flow of electrons
State the equation linking charge, current and time. include units
q=i/t Charge(coulombs), Current (Amps), Time (seconds)
What can be said about the value of current at any point in a single closed loop
Current is the same at all points in a closed circuit
What two factors does the current in a circuit depend on
Potential difference (v)
Resistance (r)
What equation should be used to calculate potential difference if current and resistance are known? State the units for all 3 quantities
v=i/r Potential difference (v), Current (a), Resistance (Ω)
What is an ‘Ohmic conductor’
A conductor for which current and potential difference are directly proportional
What happens to the resistance of a filament lamp as the temperature increases
Resistance increases
What is different about current flow through diode
The current only flows through one direction
State what happens to the resistance of a thermistor as temperature increases
The thermistors resistance decreases
State what happens to the resistance of a LDR as light intensity decreases
The LDR’s resistance increases
What is one way a component can be connected in a circuit (part one)
Series
What is one way a component can be connected in a circuit (part two)
Parallel
How does the potential difference across two two components vary when connected in series
Total potential difference is shared between each component
How does the potential difference across two two components vary when connected in parallel
Potential difference across each component is the same
If two resistors are connected in parallel, what can be said about their combined total resistance
Their total resistance is less than the smallest of the two individual resistances
If two resistors are connected in series, what can be said about their combined total resistance
Their total combined resistance is equal to the sum of the two individual resistances
Describe the current in a series circuit
In a series circuit, the current is the same at all positions since the charge only has one path to flow through
Describe the current in a parallel circuit
Ina parallel circuit, the current is shared between the different branches. When the charge reaches a junction it splits
How do you connect an ammeter
In series with other components
How do you connect a voltmeter
They should be connected in parallel to other components
