EM induction in transformers Flashcards
What is a transformer
Electrical device that increase/decrease potential difference of an alternating current by the use of the generator effect.
What is supplied to a primary coil in a transformer
alternating current - continually changing direction
What does a alternating current in primary coil cause
a changing magnetic field around primary coil
The iron core is easily magnetised what does this mean?
changing magnetic field in primary coil cause changing magnetic field inside secondary coil
explain what happens as a result of a changing magnetic field inside the secondary coil
This changing magnetic field cuts through secondary coil and induces a potential difference
Why will potential difference induced be alternating
because magnetic field is continually changing
what if the secondary coil is part of a circuit
it will cause an alternating current to flow
What is the role of a transformer
change size of an alternating current
Explain the role of a step up transformer
increases the potential difference of a power source as it has more turns on secondary coil than primary coil
explain the role of a step-down transformer
decreases the potential difference in power source as it has fewer turns in secondary coil than primary coil
What happens to electricity when transmitted over large distances
current in the wire heats up resulting in energy loss
what should you do do keep power as efficient as possible
potential difference at which electricity is transmitted should increase
what happens if potential difference increases
small amount of current transmitted because if pd increases current decreases to = given input power
why is smaller current beneficial
less heat produced in wires therefore reduce energy loss in power lines and improve efficiency
what happens when current passes through a wire
heating effect causing wire to warm up resulting in loss of electrical energy as heat so reduce efficiency
Why is voltage increased at power stations
because it produced lower current due to:
IpVp = IsVs
how is high voltage achieved
by using a step up transformer you can increase voltage
why are step down transformers useful
decrease the voltage from transmission cable so its safer to distribute in homes
tell me the steps of a power station to turn a huge alternator
- fuel is burned to heat water and convert to steam to turn a turbine
- turbine connected to a electromagnet inside a generator
- as turbine spins so does the magnet inducing a large potential difference and alternating current
- coils joined parallel to produce single output
what happens to electricity when it is transferred over a large distance
the current in the wires heats them, resulting in energy loss
how can energy loss be reduced
To transmit the same amount of power as the input power the potential difference at which the electricity is transmitted should be increased
This will result in a smaller current being transmitted through the power lines
This is because P = IV, so if V increases, I must decrease to transmit the same power
what does smaller current mean
A smaller current flowing through the power lines results in less heat being produced in the wire
This will reduce the energy loss in the power lines and improves the efficiency of the energy transfer
where is a step up transformer place and step down transformer
after the power station before homes for domestic use
what are the key features needed to reduce energy losses
more efficient, high voltage , low-resistance and transformer
how do you get electromagnetic induction
- moving magnet in a coil of wire or conductor in a magnetic field
- if move the magnet in opposite direction the polarity will be reversed so current reversed
- move magnet backwards and forwards or rotating in same direction produce alternating current
what does an induced current produce
magnetic field acts against change
