Sound quiz

Sound waves in air are:

The SI unit of frequency is:

Sound travels fastest in:

The pitch of sound depends on its:

The relation between speed v, frequency f and wavelength of a wave is:

Sound of frequency below 20 Hz is called:

SONAR is used to:

The persistence of hearing is about:

Loudness of sound is related to:

Which device uses multiple reflections of sound?

Why can sound not travel through a vacuum? (2 marks)

What are compressions and rarefactions? (2 marks)

How does the speed of sound change with temperature? (2 marks)

What is meant by the quality or timbre of sound? (2 marks)

Why is the flash of lightning seen before thunder is heard? (2 marks)

Why are the ceilings of concert halls curved? (2 marks)

Name two animals that can hear ultrasound and one that produces infrasound. (2 marks)

What is the difference between a tone and a note? (2 marks)

Why does an empty room sound different from a furnished one? (2 marks)

How is ultrasound used to detect cracks in metal blocks? (2 marks)

A sound wave travels at 339 m/s. If its wavelength is 1.5 cm, find its frequency. Will it be audible? (3 marks)

A tuning fork of frequency 440 Hz produces sound in air. Find the wavelength if the speed of sound is 344 m/s, correct to two decimal places. (3 marks)

A stone is dropped from the top of a 500 m tower into a pond at its base. When is the splash heard at the top? (Take g = 10 m/s^2 and speed of sound = 340 m/s.) (3 marks)

The time period of a sound wave is 0.002 s. Find its frequency. If its speed is 340 m/s, find its wavelength. (3 marks)

A submarine emits a SONAR pulse that returns from an underwater cliff in 1.02 s. If the speed of sound in salt water is 1531 m/s, how far away is the cliff? (3 marks)

Read the passage and answer the questions. In a large auditorium, speeches sound unclear because of persistent sound caused by repeated reflections from walls and ceiling. (i) What is this persistence of sound called? (ii) Why does it make speeches unclear? (iii) Suggest two ways to reduce it. (5 marks)

Read the passage and answer the questions. A doctor uses a stethoscope to listen to a patient's heartbeat. The sound travels through the tube to the doctor's ears. (i) What phenomenon of sound does a stethoscope use? (ii) Why does the sound not spread out and become faint? (iii) Name one other device that uses the same principle. (5 marks)

Read the passage and answer the questions. A pregnant woman undergoes an ultrasound scan, which produces an image of the baby on a screen. (i) What is ultrasound? (ii) Why is it safe to use? (iii) Name one other medical use of ultrasound. (5 marks)

Read the passage and answer the questions. Bats fly in the dark and catch insects without colliding with obstacles. They emit high-pitched sounds and detect the reflections. (i) What kind of sound do bats emit? (ii) How do they locate obstacles? (iii) Name the man-made system that works on the same principle. (5 marks)

Read the passage and answer the questions. A boy shouts near a hill and hears the echo after 1.5 s. The speed of sound in air is 340 m/s. (i) Find the distance of the hill. (ii) What is the minimum distance needed to hear an echo? (iii) Would the echo be heard sooner or later on a hotter day? Why? (5 marks)

Draw a labelled diagram showing compressions and rarefactions produced by a vibrating tuning fork. Explain how sound propagates through air. (6 marks)

Draw wave diagrams to show (i) a soft and a loud sound of the same frequency (ii) a low and a high pitched sound of the same amplitude. Explain loudness and pitch. (6 marks)

Describe, with a labelled diagram, an experiment to verify the laws of reflection of sound. (6 marks)

Draw a labelled diagram of SONAR. Explain how it is used to find the depth of the sea and solve: the echo returns in 4 s with speed of sound in water 1500 m/s. (6 marks)

Draw a labelled diagram of the human ear. Explain how sound waves are converted into signals sent to the brain. (6 marks)