Speakers & microphones

Question 1

What do loudspeakers and microphones do?

Answer 1

• They both convert between sound waves and electrical signals
• Speakers: convert electrical signals into sound waves
• Microphones: convert sound waves into electrical signals

Question 2

Structure of a loudspeaker

Answer 2

• Cone (moves wich produces sound waves)
• Coil (attached to cone which causes the cone to move)
• Permenant magnet (coil is wrapped around)

Question 3

How does a loudpeaker work?

Answer 3

• Alternating current flows through coil and causes a magnetic field
• Magnetic field of coil interacts with magnetic field of permanent magnet and causes the coil to move back and forth (alternating current)
• This causes the cone to move back and forth, because these movements are so fast, vibrations cause variations in the air, resulting in sound waves

Question 4

Structure of a microphone

Answer 4

• Diaphragm (moves due to sound waves)
• Coil (attached to diaphragm)
• Permenant magnet (coil is wrapped around)

Question 5

How does a microphone work?

Answer 5

• Sound waves hit the diaphragm, causing it to vibrate
• Causes coil, which is attached to diaphragm, to move
• Moving of coil within the magnetic field of the permanent magnets generates a current
• Frequency and amplitude of the sound waves determines how much the coil moves and therefore, the frequency and amplitude of the current

Question 6

What type of current is used in loudspeakers and microphones?

Answer 6

• Both involve alternating current
• As the coil moves back and forth, the direction of current is alternating