Speakers and microphones

9.A student says: 'A microphone works by converting sound into a changing current because the coil moves in a magnetic field.' Is this statement correct?

10.Which of the following correctly describes the energy conversion in a speaker?

11.What is the role of the permanent magnet in a speaker?

12.A student makes a speaker with a coil of 20 turns. To make the sound louder, she doubles the number of turns to 40. Which other change would also make the sound louder?

13.A microphone has a coil of wire that moves in a magnetic field. The coil moves 100 times per second. What is the frequency of the alternating current produced?

14.A student connects a microphone to an oscilloscope. When she speaks into the microphone, the oscilloscope shows a waveform with a large amplitude. What does this indicate about the sound?

15.In a speaker, the cone vibrates at a frequency of 440 Hz. What is the frequency of the sound wave produced?

16.Which of the following is true about a microphone?

17.A student has a speaker with a coil of 50 turns. She wants to make it produce a sound that is twice as loud. Which combination of changes would achieve this?

18.A microphone diaphragm vibrates due to a sound wave. The vibration causes a coil to move in a magnetic field. What is produced in the coil?

19.Which part of a speaker vibrates to produce sound?

20.A student sets up an experiment with a coil of wire connected to a sensitive ammeter. She moves a bar magnet in and out of the coil. The ammeter shows a reading that changes direction. What does this demonstrate?

21.A sound wave causes a microphone diaphragm to vibrate with an amplitude of 2 mm. If the sound becomes louder, what happens to the amplitude of vibration?

22.What type of current is used in a speaker to make the cone vibrate?

23.A student has two identical speakers. Speaker A has a coil with 100 turns, speaker B has a coil with 200 turns. Both are connected to the same alternating current. Which speaker produces a louder sound?

24.A student connects a coil of wire to a sensitive ammeter and moves a bar magnet in and out of the coil. The ammeter shows a reading. Which statement explains this observation?

25.A student has a speaker with a coil of 50 turns. She wants to make the sound louder. Which of the following changes would NOT make the sound louder?

26.In an experiment, a microphone is connected to an oscilloscope. When a sound wave of constant frequency but increasing amplitude reaches the microphone, what change is observed on the oscilloscope?

27.A student builds a simple speaker using a coil, a magnet, and a paper cone. She connects the coil to a battery. What will happen?

28.Which of the following correctly describes the energy conversion in a microphone?

29.A student investigates how the number of turns in a speaker coil affects the loudness. She uses a constant alternating current and measures the sound level with a decibel meter. Which graph shows the expected relationship?

30.A student connects a microphone to an oscilloscope. When she speaks into the microphone, the oscilloscope shows a waveform with a large amplitude. What does this indicate?

31.A student builds a simple speaker using a coil of 100 turns, a permanent magnet, and a paper cone. She connects the coil to an alternating current supply. She then replaces the permanent magnet with a stronger one. What effect does this have on the sound produced?

32.A microphone is connected to an oscilloscope. A sound wave of frequency 256 Hz and amplitude 1.0 mm causes the diaphragm to vibrate. The diaphragm is attached to a coil of 50 turns in a magnetic field of 0.2 T. What is the frequency of the alternating current induced in the coil?

33.A student investigates how the loudness of sound from a speaker depends on the current in the coil. She uses a constant alternating current and measures the sound level with a sound meter. She repeats the experiment with different currents. Which graph shows the correct relationship between current and sound level?

34.A student has two identical speakers. Speaker A has a coil with 100 turns, speaker B has a coil with 200 turns. Both are connected to the same alternating current supply. What is the ratio of the force on the coil of speaker B to the force on the coil of speaker A?

35.A student sets up an experiment with a coil of wire connected to a sensitive ammeter. She moves a bar magnet in and out of the coil. The ammeter shows a reading. She then moves the magnet faster. What happens to the reading on the ammeter?

36.Which of the following is NOT a way to make a speaker produce a louder sound?

37.A microphone diaphragm vibrates 440 times per second due to a sound wave. The diaphragm is attached to a coil in a magnetic field. What is the frequency of the alternating current produced in the coil?

38.A student connects a microphone to an oscilloscope. She speaks into the microphone with a constant pitch but varying loudness. Which of the following describes what she sees on the oscilloscope?

39.In a speaker, the cone vibrates at a frequency of 1000 Hz. What is the period of the sound wave produced?

40.A student builds a speaker with a coil of 50 turns. She wants to make the sound twice as loud. She increases the current to twice its original value. What else should she do to ensure the sound is exactly twice as loud?

41.Which of the following is a part of a speaker?

42.Any time a current passes through a wire, a magnetic field is formed around the wire.

43.A microphone contains a diaphragm which vibrates when sound reaches it.

44.An alternating current is one that always flows in the same direction.

45.If a coil moves in a magnetic field, a current is made.

46.If the current in the coil in a speaker is decreased, the sound made by the speaker is louder.

47.In a microphone, what causes the coil of wire to move?

48.A student builds a simple speaker with a coil of 50 turns. She wants to make the sound louder. Which single change would achieve this?

49.Match each part of a speaker to its description.

50.Arrange the steps in the correct order for how a speaker produces sound.

51.Name the three parts of a speaker.

52.Describe how a speaker makes a sound.

53.Complete the sentence about the energy conversion in a microphone.