T - 2 Electricity Flashcards
Equation for charge?
Charge(C) = Current (A) x Time (S)
Equation for potential difference?
Potential difference(V) = Current(A) x Resistance(Ω)
What is the trend of current and potential difference in an ohmic conductor?
Current is directly proportional to the potential difference
What happens to resistance when current changes in ohmic conductor?
resistance remains constant
As the temperature of the filament lamp increases, what happens to the resistance?
The resistance of a filament lamp increases
How does the current in a diode flow?
Current flows in one direction only
Does a diode have a high or low resistance?
The diode has a very high resistance
Which direction does the resistance go in a diode?
The reverse direction of current flow.
What are diodes useful for?
Controlling flow of current in circuit
What does a LED do when a current flows through?
Gives off light
What happens to resistance of an LDR as the light intesnisty increases?
The resistance of an LDR decreases
What happens to the resistance of a thermistor when the temperature increases?
The resistance of a thermistor decreases
How is the potential difference distributed in series circuit?
potential difference is shared between all components
How is current distributed in series circuit?
Current is same through each component
How is resistance distributed in a series circuit?
Resistance is shared between all components
How is potential difference distributed in a parallel circuit?
potential difference is the same across each component
How is current distributed in a parallel circuit?
Current is shared between all components
What happens to resistance in parallel circuit when more components are added?
The total resistance decreases
What happens when a component breaks in a parallel circuit?
The circuit continues
What happens when a component breaks in a series circuit?
The circuit stops
What is the direction of a current in an alternating current?
current changes direction back and fourth
What is the direction of a current in an direct current?
Current flows in one direction
What current is mains electricity?
Alternating current
Benefit of using alternating current?
Allows to uses a transformer
What is the frequency of mains electricity?
50hz
What power supply is mains electricity?
Ac supply
What is the potential difference of mains electricity?
230 V
How are electrical appliances connected to the mains electricity?
Three core cable
What is the colour of the live wire?
brown
What is the colour of the neutral wire?
blue
What is the colour of the earth wire?
green and yellow stripes.
What does the live wire do?
Carries alternating potential difference from the supply
What does the neutral wire do?
Completes the circuit
What does the earth wire do?
Stop appliance becoming live
What is the potential difference at live wire?
230v
What is the potential difference at neutral wire?
0v
What is the potential difference at earth wire?
0v
Why is the live wire dangerous even when switch is open?
The wire still has a high voltage
How does the earth wire stop an electric shock? x3
- Case is attached to earth wire
- Earth wire is connected to ground
- Fuse melts and shuts off current
2 Equations for power in electricity?
Power(W) = Potential difference(V) x current(A)
Power(W) = current^2(A) x resistance(Ω)
What does the amount of energy an appliance transfers depends on? x2
-How long the appliance is switched on for
-The power of the appliance.
2 equations for energy transfer?
energy transferred = power × time
energy transferred = charge flow × potential difference
What is the national grid?
A system of transformers and cables
What do step up transformers do?
Increase potential difference
What do step down transformers do?
Decrease potential difference
Why do step up transformers increase potential difference?
To stop energy loss in transmission cables
What happens when insulating materials are rubbed against each other?
They become electrically charged
What happens to electrons when insulating materials are rubbed against each other?
Electrons are rubbed off one material and on to the other.
What happens when two electrically charged objects are brought together?
They exert a force on each other
What happens to the force when the distance between the charged objects decrease?
The force gets stronger