TOPIC P2 - Electricity Flashcards
What is the formula for charge?
Charge = current x time
Q = It
What is electric current?
Flow of electric charge
Unit of current?
Amperes
What is potential difference?
Driving force that pushes the charge round. (V)
What is the influence of resistance on current flow
The greater the resistance across a component, the smaller the current that flows
Potential difference, current & resistance formula?
Potential difference (volts) = current (Amps) x resistance (ohms)
V=IR
What does an Ammeter do? Where must It be placed in relation to the circuit?
Measures current in amps flowing through a wire. It MUST be placed in SERIES
What does the voltmeter do? Where must it be placed in relation to the circuit?
Measures potential difference across the wire, in volts. It MUST be placed in PARALLEL around what you are investigating.
What sort of resistance do ohmic conductors have?
Constant resistance
At a constant temperature what happens to the current flowing through an ohmic conductor?
It is directly proportional to the potential difference across it
What does an ohmic conductor graph look like?
Diagonal line from bottom left to top right, Directly proportional
What does a Filament lamp graph look like?
Curved - as it gets hotter, less current can flow per p.d meaning the graph becomes shallower
What does a diode graph look like?
Current will only flow in one direction. Very high resistance in the reverse direction
What is an LDR
A resistor dependent on light. In bright light resistance falls and vice versa
What is a Thermistor?
A temperature dependent resistor - in hot conditions resistance drops and vice versa
What Is a series circuit?
Different components are connected end to end. Removing one element causes the circuit to break.
In a series circuit is potential difference shared?
Yes. V(total)=V(1)+v(2)+….
Is the current the same in a series circuit?
Yes, the same current flows through all components. I(1)=I(2)=….
What happens to resistance in a series circuit?
Resistance adds up.
R(total)=R(1)+R(2)
What is a parallel circuit?
Each component is seprately connected to the +/- of the supply. If you remove one element, the circuit will still function.
What is the difference in series and parallel circuits regarding potential difference.
In a parallel circuit potential difference is the same across all components whereas in a series circuit p.d is shared.
In a parallel circuit what happens to current?
Current is shared between branches. I(total) = I(1) + I(2)
