Generators, Loudspeakers And Microphones

Question 1

what do generators do and what do they look like

Answer 1

• they apply a force to rotate a coil in a magnetic field

- they look like a motor

Question 2

how do generators work

Answer 2

• as the coil or magnet spins
• a current is induced in the coil
• this current changes direction every half turn

Question 3

what are dynamos and what do they have

Answer 3

• they are d.c. generators

- and they have a split ring commutator

Question 4

what does the split ring commutator do

Answer 4

it swaps the connection every half turn to keep the current flowing in the same direction

Question 5

what do alternators have compared to dymanos (they work the same way)

Answer 5

• instead of a split ring communator

- they have slip rings and brushes

Question 6

why do alternators not have a split ring commutator

Answer 6

• so the current doesnt swap every half turn
• means that the alternator produces an alternating pd and therefore an alternating current if the coil is part of a complete circuit

Question 7

what do microphones do

Answer 7

they use electromagnetic induction to generate electrical signals

Question 8

how do microphones work

Answer 8

• sound waves hit a flexible diaphragm that is attached to the coil of a wire
• the coil of wire surrounds one pole of a permanent magnet
• and is surrounded by the other pole
• this means that as the diaphragm moves (along with the coil) a current is generated in the coil

Question 9

what does the movement of the coil in the microphone depend on

Answer 9

• the properties of the sound waves

- as louder sounds make the diaphragm move further

Question 10

what is the end result of how a microphone works

Answer 10

the microphone has converted pressure variations of a sound wave into variations in current in an electric field

Question 11

what is the diaphragm replaced with in a loudspeaker

Answer 11

a paper cone

Question 12

how does a loudspeaker work

Answer 12

• the coil is wrapped around one of the poles of a permanent magnet
• so the alternating current signal causes a force ob the coil, which moves the cone
• when the current is reversed ,the force acts in the opposite direction

Question 13

what is the effect of how the loudspeaker works

Answer 13

• the movements make the cone vibrate
• which makes t he air around the cone vibrate
• which creates variations in pressure and therefore a sound wave