P1 Electricity Flashcards
What are the two types of electric charges
Positive charge
Negative charge
What charges attract
Positive and negative (opposites)
What charges repel
The same:
Positive and positive
Negative and negative
What are charges
A property of a particle or object
What charge do protons have
Positive
What particle has a negative charge
Electrons
What type of charge do Neutrons have
None - it’s neutral
What are particles
Smaller parts of atoms
How many charges do atoms contain
An equal number of protons and electrons - over all an atom has no charge
How does a storm use Charge
The charges move around the cloud producing regions that have a + or - charge. Electrons jump from different charges areas and produces a big current.
What is an electric field
A region where a charged material or particle experiences force
Where is an electric field
Around a charge
What is a current
The amount of charge flowing per second
What does the switch do
Opens and closes a gap in the circuit- you close the gap to complete the circuit and open it to cut the current off
How do you measure current
With an ammeter
What unit is current in
Amps (A)
Where do charges come from
The charges are already in the wires
How do charges move around a circuit
The cell (battery) pushes it around the circuit
How does a rope model show what happens in wire when current flows
One person pulls the rope and the other grips it lightly - the rope moves around.
The rope represents the charges in a circuit and the amount of rope moving past a point per sec is the charge
What is potential difference
The push provided by a cell or battery to make the charges move
What does the p.d. across a cell tell you
The size of the force on the charges
How do you measure potential difference
Using a voltmeter
The is the unit and measurement for p.d.
Volts (V)
How do you measure the p.d. Across a cell
Connecting the voltmeter across it - this is also called the rating
What is the current in a series circuit like
The same through out
What is the p.d. in a series circuit like
Shared between each components
What is the current in a parallel circuit like
The ammeter measuring the battery is the sum of the other ammeters measuring other components
What is the p.d. in a parallel circuit like
The voltage is the same in each branch
What are the two types of circuits
Series and Parallel
What are the factors of a series circuit
All the bulbs are formed on one loop (old Christmas lights)
What is the main factor of a parallel circuit
More that one loop (branch)
What’s the benefit of a parallel circuit
If one bulb breaks all the others stay on
What is the current like in a series circuit
The current is the same everywhere. If you add components then the current will get smaller
What is the current like in a parallel circuit
The currents in all the branches of the circuit add together to make the total current. If you add another branch the total current increases and the other branches stay the same
How would you use a rope model to show a series circuit
The rope would move the same speed everywhere and as the more people hold the rope the slower the rope moves
How would you use the rope model to show a parallel circuit
There would be more loops of rope and all the loops are driven by the same ‘battery’ person
What does the resistance in a component tell us
How easy or difficult it is for charges to pass through the component
What is the unit for resistance
Ohms (Ω)
What does the current depend on
The push of the battery and the resistance of the component
How do you calculate the current
Current(A) = potential difference(V) .\’ resistance(Ω)
How can you use resistance
To explain why the current decreases as you add more bulbs in a series circuit (adding more bulbs increases the resistance so the current is less)
How do you calculate resistance
Resistance(Ω) = p.d. (V) .\’ current (A)
How do you model resistance
Using marbles - if you had a slop (at the top marbles and on the ramp posts) as the marbles fall down they act like electrons and the posts represent resistance
What is a conducter
A material that conducts charge or energy well, such as a metal or graphite
What makes metals good conductors
Because they have very low resistance as they contain lots of electrons that can move the resistance of a 10m piece of copper wire is 0.2Ω
Why are plastics such bad conductors
Because they don’t have as many electrons that are free to move. The resistance of plastic objects is very high (over a thousand million million ohms)
What are insulators
A material that does not conduct electrical or transfer energy well
Which poles of the magnet repel
The same ones -
North and north
South and south
Which of the poles on a magnet attract
Opposite-
North and south
What are the materials that are attracted to magnets called
Magnetic materials (iron, nickel, cobalt)
What is an electric field
Where there is force on a charge
What is a magnetic field
When there is force on a magnet or a magnetic material
How do you find out the shape of a magnetic field
Using plotting compasses or iron filings
What are the lines called that represents the magnetic field
Magnetic field lines
What does it mean if the field line are closer
The magnetic field is stronger
What is a permanent magnet
A magnet that has its own magnetic field
Why would a magnet line up with north and south if you hang it
Because of the Earths magnetic field
What is an electromagnet
A temporary magnet produced using an electric current
How do you make an electromagnet
Make a circular loop of wire and pass a current through it - the magnetic field lines are straight at the centre of the loop. A singular loop isn’t very strong so if you put lots of loops together the field is a lot stronger.
How do you turn an electromagnet on and off
By turning the current on and off - the magnet only works with current running through the wire
What is a core
The magnetic material in the centre of the coil - this makes the electromagnet much stronger
What are most cores made of
Iron because it is easy to magnetise but it loses its magnetism easily
What would be a good material to make a coil out of if you wanted it to stay magnetic when off
Steel
How do you make an electromagnet stronger
Add more turns or loop on the coil
Add more current flowing through the wire
The type of core it has
What is the main differences between permanent magnets and electromagnets
You can turn an electromagnet on and off
You can make electromagnets much stronger than permanent magnets
How do trains use electromagnets
Beginners use magnets repelling to build trains use if magnetic levitation - the train is lifted by magnets.
Powerful electromagnets on the track repel magnets on the train - there is no friction so it can go faster
What is relay
Electrical device that uses current flowing through it in one circuit to switch on and off a current in a second circuit
Why can X-Rays be dangerous
That have a very high Potential difference
How does a relay work
A relay uses a small current in a circuit to operate a switch on another. When the switch is closed the coil becomes an electromagnet- the two pieces of iron inside are magnetised they attract each other an turn on the second circuit
How can you use an electromagnet magnet to sort metal
Iron and steel will be attracted to it but other metals like aluminium won’t
What is a motor
A component or machine that spins when a current flows through it
How do you make a simple motor
Using two magnets and a coil of wire.
Connect the coil to a battery allows a current to flow in the coil - it’s now an electromagnet. The forces between the coil and permanent magnet makes the coil spin
