Electricity Flashcards
State the equation that links charge, current and time
Charge = Current x Time
What are the units for charge?
Coulombs, C
What are the units for current?
Amps, A
What are the units for time?
Seconds, s
State the equation that links current, potential difference and resistance
Potential difference = Current x Resistance
What are the units for potential difference?
Volts, V
What are the units for resistance?
Ohms, Ω
What is a series circuit?
A circuit with only one pathway for current to flow
What is a parallel circuit?
A circuit with more than one pathway for current to flow
What happens to current in a series circuit?
It is the same anywhere in the circuit
What happens to potential difference in a series circuit?
It is shared between the components
What is the resistance in a series circuit?
The total resistance is the sum of the resistance of each component
What happens to current in a parallel circuit?
It is shared between the different pathways
What happens to potential difference in a parallel circuit?
It is the same for all components
What is the resistance in a parallel circuit?
The total resistance is the less than the component with the smallest resistance
Describe the relationship between current and potential difference for a resistor
Current and potential difference are directly proportional
Describe the resistance through a diode
Resistance is low in one direction, but very high in the opposite direction
Describe the relationship between resistance and temperature for a thermistor
As temperature increases, resistance decreases
Describe the relationship between resistance and temperature for an LDR
As light intensity increases, resistance decreases
Name two sources of direct current
Battery and cell
Name a source of alternating current
Mains
What is direct current?
Current that flows in one direction only
What is alternating current?
Current that continually changes direction
What is the potential difference of mains electricity?
230V
What is the frequency of mains electricity?
50Hz
Define power
The rate at which energy is transferred OR the rate at which work is done
What are the units for power?
Watts, W
What are the units for energy?
Joules, J
What are the units for work done?
Joules, J
What equation links energy, power, time?
Power = Energy / Time
What equation links power, time and work done?
Power = Work done / Time
What equation links current, potential difference and power?
Power = Potential difference x Current
What equation links current, resistance and power?
Power = (Current)2 x Resistance
What colour is the live wire?
Brown
What colour is the neutral wire?
Blue
What colour is the Earth wire?
Green and yellow striped
What is the function of the live wire?
Carries the potential difference at 230V
What is the function of the neutral wire?
Completes the circuit, is at 0V
What is the function of the Earth wire?
Safety wire, carries the potential difference if the appliance becomes live
Why does touching the live wire cause electric shock?
The difference in potential difference between our body and the live wire is 230V, this forces a current through the body and causes electric shock
What equation links charge, energy and potential difference?
Energy = Charge x Potential difference
What is the National Grid?
A network of cables and transformers that transport electricity from power stations to consumers
How do step-up transformers affect potential difference and current?
Increase potential difference and decrease current
How do step-down transformers affect potential difference and current?
Decrease potential difference and increase current
Why is electricity transmitted at very high potential difference?
This reduces current, which reduces heating of the wires, which reduces energy loss
Why is electricity delivered to homes at lower potential difference?
So it is safer for people to use
Draw the symbols for each component:
Open switch, closed switch, lamp, cell, battery, voltmeter, ammeter, fuse, diode, variable resistor, thermistor, resistor, LED, LDR
