p15

Question 1

describe how a microphone works

Answer 1

they convert sound waves into electrical singals
- sound waves cause the diaphragm to vibrate
- this causes the coil to vibrate
- the coil cuts through the magnetic field
- a pd is induced across the coil
- a current is induced in the coil
- the current changes direction because the coil is constantly changing direction

Question 2

describe how a loudspeaker works

Answer 2

converts electrical signals into a sound wave
- current flows through the coil
- as coil is in magnetic field, there is a force on the coil
- the current is alternating so force on the coil is constantly changing direcion
- this causes the coil to vibrate
- the coil is attached to a cone
- the cone vibrates producing a sound wave

Question 3

what happens when alternating pd is applied across the primary coil of a transformer

Answer 3

• the alternating pd in the primary coil causes an alternating current
• this causes an alternating magnetic field in the iron core
• which induces alternating pd across the secondary coil

Question 4

what is a primary coil

Answer 4

it has a certain pd applied to it and a number of turns on it

Question 5

what is secondary coil

Answer 5

it gives a certain pd and has a number of turns on it

Question 6

differences and similarites between step up and step down transformer

Answer 6

• both have laminated core made from a magnetic material
• both have two cores
• coils are both made from an electrical conductor
• step up transformer has more coils on the secondary coil and it increases the voltage, but step down decreases the voltage

Question 7

what is motor effect

Answer 7

When a conductor carrying a current is placed in a magnetic field the magnet producing the field and the conductor exert a force on each other

Question 8

generator vs motor effect

Answer 8

The generator effect is when a current is induced in a wire which is experiencing a changing magnetic field while the motor effect is when a current carrying wire’s magnetic field interacts with the magnetic field around it, resulting in a force being exerted on it, causing it to move.
- generator turns movement into current whereas motor turns current into movement