Year 8 Electricity Flashcards
What flows in an electronic current
Electrons
What a the flow of electrons called
A current
What is the voltage
The size of the ‘push’ provided by a cell
What device measures current
Ammeter
What is the unit used for a current
Amperes (A)
What does a voltmeter measure?
Potential difference
What unit is used to measure potential difference?
Volts (V)
True/false. In a series circuit the current is the same at any point in the circuit.
True
What is a conventional current?
This is where the electrons are pushed away from the negative terminal of the cell.
What is a series circuit?
This is where everything is placed on a loop from negative to positive terminal
What is a parallel circuit?
A circuit that contains more than on possible path for the current to flow round.
What is resistance?
Conductors have low resistance and insulators have high resistance, this is how much the material will try to stop the electrons from flowing through them.
What is resistance measured in?
Ohms (Ω)
What symbol does current have?
I
What symbol does resistance have?
R
What symbol does potential difference have?
V
What is a diode?
Something that allows a current to flow in one direction
What does a rheostat do?
Changes the amount of current flowing through a circuit.
What happens in an AND gate?
Both switches must be on to get an output
What is the calculation to calculate resistance?
R=V/I
What does ‘DC’ stand for?
Direct current ( electrons only flow in one direction)
What does ‘AC’ stand for?
Alternating Current ( this current changes direction at a regular rate )
In power lines, how is electricity transported as?
AC / alternating current
How many volts are in a normal wall plug?
230V
What happens during a short circuit?
The live and neutral wire cross causing a large current.
How does a fuse protect you?
It melts when there is a short circuit and breaks the circuit
When are ‘Earth’ wires used?
If an appliance has a metal case
What is the definition of power?
The rate at which energy is transfered
What is power measured in?
Watts ( W )
What is the calculation for Power?
Power = Voltage x Current
How can a charged body be discharged?
By connecting it to earth with a conductor
How does lightning happen?
It happens when clouds discharge through the air
What happens when you rub a balloon on your head?
The negatively charged electrons are “ rubbed off “ onto your hair. Your hair becomes negatively charged.
What happens when to bodies that carry the same type of charge come together?
They repel
What happens when to bodies that carry opposite charges come together?
They attract
True / False. Charged objects attract small objects like dust particles.
True
Which 3 metals are attracted to a magnet?
1) Iron ( and steel which is over 90% Iron)
2) nickel
3) cobalt
Where is the magnetism of a magnet concentrated?
The poles ( north and south)
Fact! Two opposite poles attract each other.
What is a magnetic field?
The area around a magnet where it has magnetic effect.
Rules about magnetic fields.
1) the field lines point from north poles to south poles.
2) the field lines never cross
3) where the lines are close together the field is strong and where the lines are further apart, the field is weaker.
