Beath High School - Int 1 Physics1 Intermediate 1 Physics Sound and Music Questions and Answers.

Beath High School - Int 1 Physics 1

Intermediate 1 Physics Sound and Music

Questionsand

Answers


Intermediate 1 Physics

Sound and MusicSound Waves Q 1 to

8Speed of Sound Q 9 to 12Using Sound Q 13 to 17

Amplified Sound Q 18 to 22


1. An orchestra has various sections - like string, brass, percussion etc.....(a) How do all musical instruments produce sound energy?

All instruments produce sound by

vibrations.(b) Complete the following:

Sound is a which transfers .

wave

Sound Waves

energy


2. Which of the following are the units of frequency?A watts B decibels C hertz D volts.

Answer: C


3. An oscilloscope can display a musical note on the screen.

Two waves

50 waves in one second

(a) How many waves are seen on the screen?

(b) The frequency of these waves is 50 Hz.How many waves are produced in one

second?

microphone

Oscilloscope Screen


4. Jane uses a signal generator to increase the pitch of the note emitted by the speaker.The signal generator has an amplitude control and a frequency control as shown.

(a) Which control did Jane turn?

She turned the frequency control.

Frequency control

Amplitude control


Jane now connects an oscilloscope to the generator and adjusts the amplitude and frequency controls.

(b) What did Jane do to the loudness of the note

emitted? Explain your answer.

The note is louder as the wave is taller on the

screen.

Oscilloscope trace before Jane adjusts the controls

Oscilloscope trace after Jane adjusts the controls


(c) What did she do to the frequency of the note?

Explain your answer.

She has increased the frequency of the note as there

are more waves on the screen.

Oscilloscope trace before Jane adjusts the controls

Oscilloscope trace after Jane adjusts the controls


5. Jason generates sounds by striking tuning forks.The first tuning fork he uses is shown below.

128 Hz

He strikes the tuning fork and produces a note of frequency 256 Hz. The second tuning fork he strikes produces a note one octave higher than the first. (a) What is the frequency of the second tuning fork?

512 Hz

(b) What would be the frequency of a note one octave below the original?

256 Hz


6. Guitar strings are being tested using the setup shown below.

Make the string tighter by hanging more weights

on the end or make the string shorter by moving

the bridge closer to the fixed end.

The string is plucked and a note of 300 Hz is produced.State two ways that this setup could be changed to increase the frequency of the note produced.

Guitar string


7. A set of identical measuring cylinders are filled with different volumes of water. A tune can be played by blowing across the mouth of the cylinders.

There are different lengths of air column to vibrate

A, B, C

(a) Explain why each cylinder produces a different note.(b) Which cylinder produces the highest frequency.

Explain your answer.

A B C

(c) List the cylinders in order of increasing frequency.

Cylinder C because it has the shortest column of air to vibrate


8. Two students are investigating how the frequency of sound produced by a stretched wire alters as the thickness of the wire is varied. Their results are shown here.

The length of the wire

(a) Which factor, other than thickness affects the results?

1

1

2

3

4

Thickness ofwire (mm)

Length of wire(m)

0.5

1

0.5

0.25

0.5

Frequency of sound (Hz)800

400

400

530

200


(b) Construct a new table, with headings and units, to show three results which the students should use to enable them to make a conclusion from their investigation.

Thickness of wire (mm)

Frequency of sound (Hz)

1 800

2 400

4 200

(c) What conclusion can the students make from their investigation?

The thinner the wire the higher the note.


9. A block of flats have to be demolished. When the explosive is detonated, the observers, who are a safe distance away, hear nothing. They see the flats collapsing and sometime later hear the sound of the explosion.

You see the lightning before you hear the thunder during a storm

It takes the sound a few seconds to travel the distance between the flats and the observers.

Speed of Sound

(a)Explain why nothing is heard immediately.

(b) Give another example of this effect.


10. Two pupils are given the task of measuring the speed of sound in air. They are given an air horn and a flag. Describe how they could measure the speed of sound in air.You should:

(a) state any extra apparatus they would need They would need a measuring tape and a stop

clock (b) state the measurements to be taken Measure out a distance of more than 200m and turn to see the other pupil. Wave the flag and sound the horn at exactly the same time. Start the stop clock when you see the flag wave and stop the clock when you hear the horn.

(c) state how the speed is calculated.

Calculate the speed of sound from distance/time.


11. Sound waves pass through a long pipe. When the sound reaches sound sensor I the timer is switched on. After the sound has travelled 10 metres the sound reaches sound sensor 2 and the timer is switched off.

Speed = distance/time = 10/0.029 = 344.8 m/s

10 m

0.000

Sound sensor 1 Sound sensor 2

Source ofsound waves Timer : displays the time taken in seconds.

0.029

The final display on the timer, in seconds, is shown below.

Calculate the speed of the sound


12. A student wants to find the speed of sound in air using the echo from a wall.

She stands 300 metres away from a large wall as shown.

She now hits the drum and at the same time starts a stop clock. When she hears the echo of the drum she stops the clock. The reading from the stop clock is 1.8 seconds.Use these figures to calculate the speed of sound in air.

Speed = distance/time

= 600/1.8

= 333 m/s

Girlwithdrum

300 m

Wall


13. Sound can travel through air. Name four other substances through which sound can travel - include a solid, a liquid and a gas.

Using Sound

Wood, glass, water and carbon dioxide. (or any other sensible answers!!)


14. Two astronauts are working on the surface of the Moon. They are about 5 metres away from each other. One astronaut has a sound sensor on the outside of his spacesuit. The other astronaut hits two metal hammers together.

(a) Will the sound sensor detect the sound? Explain your answer.No, because there is no atmosphere on the moon and there will be no particles to carry the sound energy from the hammers to the sensor. (b) One of the astronauts hits a rock with a hammer.Will a sound sensor in the nearby spacecraft detect the sound?

Yes, because the sound will travel through the ground to the sensor.


15. In class, a signal generator is adjusted to the frequency shown.

It is producing a sound above 20000 Hz which means that humans cannot hear it.

Robert tells the teacher that he can hear the note from the loudspeaker. (a) Why does his teacher tell him that he is mistaken?

(b) State a frequency that would probably be heard by the whole class.From about 20 Hz up to about 16000 Hz to be sure everyone hears it.

1

2

4

3

Hz x 10 000


16. A special sound generator is being tested in a school laboratory.A detector with a meter is needed to pick up the sound since the frequency is beyond the range of human hearing.

(a) What is the name of this type of sound? Ultrasound

(b) Which mammal might be able to hear this

sound?

Sound Generator

Bats, dogs or dolphins


16. (c) This type of sound has an important medical use.Describe what it is used for.

It can be used to check on a baby inside the mother’s womb or it can be used to break up kidney stones or gall stones

(d) It is not only medical staff who use this type of sounding equipment.In what industry might it be used and how is it put to good use?

Fishermen use it to search for fish (sonar).


17. This poster appears on the wall of a hospital waiting room but part of the poster has been torn and some words are missing.(a) What is the missing word after "sound level in ..... "? Decibels

(b) The source of sound with a level of 120 is also torn out of the poster. This source is a source of noise pollution. Give some possible examples of noise pollution.

(c) Why does the lower section of the poster carry a warning?

Sounds over 90 dB can damage your

hearing

Any unwanted sound is noise

pollution!

source of noise sound level in

silence 0

whisper 20

normal conversation 60

warning level

heavy traffic 90

120


18. Four oscilloscope traces are shown. The oscilloscope controls are all at identical settings.

Trace A is the input signal to an amplifier.

Amplified Sound

(a) Which trace shows the output signal of the same amplifier?

A B

C D

(b) The input signal has a frequency of 200 Hz. State the frequency of the output signal.

Signal D

200 Hz


19. The science technician is checking the amplifier used in the school tannoy system.She connects a voltmeter to the input terminals of the amplifier and obtains the reading shown.When she checks the output voltage from the amplifier

the new reading is 30 V.(a) How will she calculate the voltage gain of the

amplifier?

(b) What is the gain of this amplifier?

Use the equation voltage gain = voltage

out/voltage in

0 1 .5 VACV

voltage gain = voltage out/voltage in

= 30/1.5 = 20


20. Music albums are available in tape cassette or compact disc (CD) format. Cassettes are less expensive, yet CDs are very popular and sell in great numbers.

(a) State two advantages of a CD compared to a tape cassette.Any two from easier to store, high quality sound, no wear and tear of the disc, very little background noise

(b) A tape cassette can be used to record your own voice and then played back. However the recording is not immediately recognisable as your own voice. Why is this?

We are hearing from the vibrations through the air only. Usually we hear the vibrations through the bones in our skull as well.


21. Laura whistles into a microphone connected to an oscilloscope. The trace produced on the oscilloscope is shown below.

Answer: D

Laura now whistles a louder sound with the same frequency into the microphone. Which trace shows the new wave pattern produced on the oscilloscope if the controls are not changed?A

C

B

D


22. A public address system is used at airports to give passengers information.It is made up of three components, as shown below.

Microphone: converts sound into an electrical signal.

Microphone Amplifier Loudspeaker

State the function of each of these components,

Amplifier: makes the electrical signal stronger.

Loudspeaker: converts the electrical signal back to

sound


Intermediate 1 Physics Sound and Music

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Beath High School - Int 1 Physics1 Intermediate 1 Physics Sound and Music Questions and Answers.

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