Ultrasound and Sonar
Ultrasound is sound with a frequency above human hearing, used in sonar and medical scans by timing reflected pulses.
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Ultrasound is sound with a frequency above human hearing, used in sonar and medical scans by timing reflected pulses.
- Frequency is above 20,000 Hz
- Distance equals speed times half the echo time
- Used for imaging unborn babies
🧠 Quick quiz
Three questions. Score 2 or more to complete the topic.
What is Ultrasound and Sonar?
Within Physics, which covers forces, energy, waves, electricity, magnetism, light and space explained through motion and experiments, this topic explains Ultrasound and Sonar. Physics topics explain how things move, push, heat up and carry energy, so each one here pairs a definition with a live model you can change.
Check that you can explain Ultrasound and Sonar in your own words and give one example from everyday life. If you can do that, you have understood the core idea.
Understanding Ultrasound and Sonar explains how the physical world behaves, from sport and transport to electricity and medicine.
Ultrasound and Sonar in detail
Ultrasound is sound with frequencies above 20,000 Hz, beyond human hearing. It is produced by piezoelectric crystals that vibrate when a high-frequency alternating voltage is applied.
Sonar uses ultrasound pulses to find the depth of the sea or locate shoals of fish by timing echoes. In medicine, ultrasound scans produce images of unborn babies and organs without ionising radiation, and focused ultrasound can break kidney stones. It is also used to detect flaws in metal and to clean delicate objects. Bats and dolphins use the same principle naturally.
How the interactive helps you understand Ultrasound and Sonar
Watch the wave in the interactive. Use any sliders or buttons it offers to change the values and see how the wave responds.
Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of Ultrasound and Sonar.
Real-life uses and examples
- Answer “explain” questions by linking Ultrasound and Sonar to a clear cause and effect.
- Predict what a ball, car or circuit will do with Ultrasound and Sonar before you do the calculation.
- Explain everyday devices, such as brakes, lifts or chargers, using Ultrasound and Sonar.
Common mistakes to avoid
- Forgetting that some quantities, such as force or velocity, also have a direction.
- Mixing up Ultrasound and Sonar with a related quantity that has different units.
- Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.
Frequently asked questions about Ultrasound and Sonar
What is Ultrasound and Sonar?
Ultrasound is sound with a frequency above human hearing, used in sonar and medical scans by timing reflected pulses.
What are the most important points about Ultrasound and Sonar?
The main points are: Frequency is above 20,000 Hz; Distance equals speed times half the echo time; Used for imaging unborn babies.
Why is Ultrasound and Sonar useful?
Understanding Ultrasound and Sonar explains how the physical world behaves, from sport and transport to electricity and medicine.
How can I practise Ultrasound and Sonar?
Open the interactive at the top of this page and change the controls one at a time. Predict the result before each change, then take the three-question quiz. A score of two or more marks the topic as complete on this device.
Which topics are related to Ultrasound and Sonar?
Related topics in Physics include Total Internal Reflection, Dispersion and Colour, Static Electricity.