Year 9 - Science
Ultrasound
Waves
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit explores the nature of sound and water waves, including transverse and longitudinal motion, wave reflection, superposition, and the speed of sound in various media. It covers sound production, detection, and auditory ranges, emphasising data interpretation, and basic calculations.
Lesson Summary
You will learn to describe what ultrasound is and explain its properties, and also describe some uses of ultrasound.
Key Notes
- 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.
Vocabulary To Learn
- 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
Common Mistakes To Avoid
- Ultrasound may be harmful to the human body (similar to X–rays).
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key 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.
2. Define this scientific word and use it in context. 'sound wave'
a 'pulse' that travels through a material, caused by forward and backward vibrations of particles. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Ultrasound may be harmful to the human body (similar to X–rays). Correction: 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.
More Lessons In This Unit
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