Starter quiz
- Which of the following are transferred by a sound wave?
- energy ✓
- particles
- vibrations ✓
-
- When a material allows a wave to travel through it, we say that the material __________ the wave.
- transfers
- transforms
- transmits ✓
- transports
-
- Which of the following is the frequency of a wave?
- the number of pulses per second ✓
- the time taken for one pulse
- the number of pulses per metre
- the length of one pulse
-
- Which of the following is the unit of frequency?
- Hz ✓
- J
- m
- Pa
- s
-
- Which of the following statements about ultrasound waves is correct?
- Ultrasound waves have the same frequency as sound waves.
- Ultrasound waves have lower frequencies than sound waves.
- Ultrasound waves have higher frequencies than sound waves. ✓
-
- Match each of the following parts of the human ear with its function.
- small bones⇔act as levers to amplify vibrations ✓
- pinna⇔funnels sound into the ear canal ✓
- ear drum⇔vibrates when a sound wave hits it ✓
- nerve⇔sends signals to the brain ✓
- cochlea⇔contains liquid, and hair cells that can produce nerve signals ✓
Exit quiz
- Ultrasound means sound waves with frequencies above…
- 20 Hz
- 200 Hz
- 2000 Hz
- 20 000 Hz ✓
- 200 000 Hz
-
- How many of the following materials can ultrasound waves travel through? air, water, soft tissue in the body.
- zero
- one
- two
- three ✓
-
- Which of the following explains why humans cannot hear ultrasound?
- Ultrasound waves burst the eardrum.
- Ultrasound waves cannot fit into the ear canal.
- Parts of the human ear cannot vibrate fast enough. ✓
- The brain cannot recognise nerve signals caused by ultrasound.
-
- Which of the following increases the rate of energy transfer by a sound wave or ultrasound wave?
- decreasing the pitch
- increasing the amplitude ✓
- increasing the frequency ✓
-
- Which of the following describes how ultrasound can be useful in physiotherapy?
- It can be used to cool body tissues.
- It can be used to warm body tissues. ✓
- It can be used to detect bone fractures.
- It can be used to see inside body tissues.
-
- Which of the following statements explain why ultrasound can be used to look inside the human body?
- It has a heating effect.
- It passes through human tissue. ✓
- It increases blood flow to body tissue.
- It reflects off boundaries between different tissues. ✓
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Worksheet
Presentation
Video
Lesson Details
Key learning points
- Sound waves of frequency below 20 Hz usually cannot be heard by humans, so are called infrasound.
- Sound waves of frequency above 20 000 Hz usually cannot be heard by humans, so are called ultrasound.
- Ultrasound waves can cause objects to vibrate, so transfer energy. They do not cause harm to the human body.
- Ultrasound can be used to image structures inside the body as it reflects from boundaries between tissues.
- Ultrasound vibrations can clean delicate objects and can help to treat injuries and illnesses in physiotherapy.
Common misconception
Ultrasound may be harmful to the human body (similar to X–rays).
Ultrasound is essentially the same thing as sound (longitudinal waves). It consists of vibrations of matter, rather than an additional entity or 'ray' that interacts strongly with matter. Compare sound of 19 999 Hz with ultrasound of 20 001 Hz.
Keywords
Sound wave - a ‘pulse’ that travels through a material, caused by forward and backward vibrations of particles
Frequency - the number of vibrations each second
Ultrasound - sound waves with a frequency above 20 000 Hz, that cannot be detected by human ears
Tissue - a group of living cells that are similar and perform a specific function
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