Electricity Flashcards
(21 cards)
What is electric current?
Electric current is the flow of electric charge. In a circuit, this is the flow of electrons around the circuit.
What is potential difference (voltage)?
Potential difference is the energy transferred per unit charge passed. It pushes the charge around the circuit.
What is resistance and what causes it?
Resistance is anything that slows down the flow of current. It is caused by collisions between electrons and the atoms in a conductor.
What happens to current in a series circuit?
In a series circuit, the current is the same at all points.
What happens to potential difference in a series circuit?
In a series circuit, the total potential difference is shared between all the components.
What happens to resistance in a series circuit when more resistors are added?
The total resistance increases because the resistors add together.
What happens to current in a parallel circuit?
In a parallel circuit, the total current is shared between the branches.
What happens to potential difference in a parallel circuit?
In a parallel circuit, the potential difference across each branch is the same.
What happens to resistance in a parallel circuit when more branches are added?
The total resistance decreases because there are more paths for the current to take.
What does a voltmeter measure and how is it connected?
A voltmeter measures potential difference and is connected in parallel across a component.
What does an ammeter measure and how is it connected?
An ammeter measures current and is connected in series in the circuit.
What is an ohmic conductor?
An ohmic conductor is a component where the current is directly proportional to the potential difference across it, at a constant temperature.
What does the current-voltage graph for a filament lamp look like and why?
It curves because as the current increases, the filament heats up and the resistance increases.
What is the function of a diode?
A diode only allows current to flow in one direction. It has a very high resistance in the opposite direction.
What is direct current (DC)?
Direct current flows in one direction only. It is the type of current supplied by cells and batteries.
What is alternating current (AC)?
Alternating current changes direction repeatedly. It is the type of current supplied by the mains electricity in the UK.
What is the frequency and potential difference of UK mains electricity?
The frequency is 50 Hz and the potential difference is around 230 V.
What is the function of the live wire in a plug?
The live wire carries the alternating potential difference from the mains supply to the appliance.
What is the function of the neutral wire in a plug?
The neutral wire completes the circuit and carries current away from the appliance. It is close to 0 V.
What is the function of the earth wire in a plug?
The earth wire is a safety wire that stops the appliance from becoming live by providing a path to ground if there is a fault.
What is Ohms Law
Relationship between voltage, current and resistance(V=IR)
