EM induction in transformers

Question 1

What is a transformer

Answer 1

Electrical device that increase/decrease potential difference of an alternating current by the use of the generator effect.

Question 2

What is supplied to a primary coil in a transformer

Answer 2

alternating current - continually changing direction

Question 3

What does a alternating current in primary coil cause

Answer 3

a changing magnetic field around primary coil

Question 4

The iron core is easily magnetised what does this mean?

Answer 4

changing magnetic field in primary coil cause changing magnetic field inside secondary coil

Question 5

explain what happens as a result of a changing magnetic field inside the secondary coil

Answer 5

This changing magnetic field cuts through secondary coil and induces a potential difference

Question 6

Why will potential difference induced be alternating

Answer 6

because magnetic field is continually changing

Question 7

what if the secondary coil is part of a circuit

Answer 7

it will cause an alternating current to flow

Question 8

What is the role of a transformer

Answer 8

change size of an alternating current

Question 9

Explain the role of a step up transformer

Answer 9

increases the potential difference of a power source as it has more turns on secondary coil than primary coil

Question 10

explain the role of a step-down transformer

Answer 10

decreases the potential difference in power source as it has fewer turns in secondary coil than primary coil

Question 11

What happens to electricity when transmitted over large distances

Answer 11

current in the wire heats up resulting in energy loss

Question 12

what should you do do keep power as efficient as possible

Answer 12

potential difference at which electricity is transmitted should increase

Question 13

what happens if potential difference increases

Answer 13

small amount of current transmitted because if pd increases current decreases to = given input power

Question 14

why is smaller current beneficial

Answer 14

less heat produced in wires therefore reduce energy loss in power lines and improve efficiency

Question 15

what happens when current passes through a wire

Answer 15

heating effect causing wire to warm up resulting in loss of electrical energy as heat so reduce efficiency

Question 16

Why is voltage increased at power stations

Answer 16

because it produced lower current due to:

IpVp = IsVs

Question 17

how is high voltage achieved

Answer 17

by using a step up transformer you can increase voltage

Question 18

why are step down transformers useful

Answer 18

decrease the voltage from transmission cable so its safer to distribute in homes

Question 19

tell me the steps of a power station to turn a huge alternator

Answer 19

• 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

Question 20

what happens to electricity when it is transferred over a large distance

Answer 20

the current in the wires heats them, resulting in energy loss

Question 21

how can energy loss be reduced

Answer 21

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

Question 22

what does smaller current mean

Answer 22

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

Question 23

where is a step up transformer place and step down transformer

Answer 23

after the power station before homes for domestic use

Question 24

what are the key features needed to reduce energy losses

Answer 24

more efficient, high voltage , low-resistance and transformer

Question 25

how do you get electromagnetic induction

Answer 25

• 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

Question 26

what does an induced current produce

Answer 26

magnetic field acts against change