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Physics Quiz - Medical Physics - Ultrasound (Questions)

In GCSE Physics you learn how ultrasound waves are used in medicine for scanning, monitoring and sometimes treatment without using dangerous ionising radiation.

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Fascinating Fact:

It is a non ionising form of radiation, so it does not carry the same risk of DNA damage as X rays or gamma rays.

In GCSE Physics, you study how ultrasound waves reflect at tissue boundaries, how echoes are turned into images on a screen, and why ultrasound is often safer than ionising radiation in medicine.

Key Terms

Ultrasound wave: A sound wave with a frequency above 20 kHz, higher than the upper limit of human hearing.
Echo: A reflected sound wave that returns from a boundary and can be detected and processed.
Non-ionising radiation: Radiation that does not carry enough energy to remove electrons from atoms and damage DNA.

Frequently Asked Questions (Click to see answers)

What is ultrasound used for in GCSE medical physics?

In GCSE medical physics, ultrasound is mainly used for scanning soft tissues, such as checking a developing baby, examining the heart, or looking at organs like the liver and kidneys.

How does an ultrasound scan produce an image?

An ultrasound probe sends high-frequency sound waves into the body. The waves reflect at boundaries between different tissues, and a computer uses the returning echoes to build a moving image on the screen.

Why is ultrasound often considered safer than X-rays?

Ultrasound is considered safer than X-rays because it uses non-ionising radiation. The waves do not carry enough energy to ionise atoms, so the risk of long-term cell and DNA damage is much lower.

Try These Related Quizzes

What is the frequency above which a sound wave is known as ultrasound?

[ ]	5,000 Hz
[ ]	10,000 Hz
[ ]	15,000 Hz
[ ]	20,000 Hz

Which of the following can be a use of ultrasound waves?

[ ]	Sonar
[ ]	Animal communication
[ ]	Foetal scanning
[ ]	All of the above

Which formula correctly relates speed, distance and time?

[ ]	Speed = Distance x time
[ ]	Distance = ^Time/_speed
[ ]	Speed = ^Distance/_Time
[ ]	Speed = ^Time/_Distance

Ultrasound waves travel approximately 1,500 m/s in water. A boat sends out an ultrasound wave to the bottom of the ocean. It takes 0.5 seconds for the wave to hit the bottom of the floor and reflect back to the detector. How deep is the ocean floor below the boat?

[ ]	350 m
[ ]	375 m
[ ]	500 m
[ ]	675 m

The speed of ultrasound in air is 330 m/s. How far away is a car if an ultrasound wave is sent to it along a road and takes 0.1 s to return?

[ ]	10 m
[ ]	14.5 m
[ ]	16.5 m
[ ]	20 m

The speed of ultrasound in metal is 5,000 m/s. How far away is a crack in the metal if an ultrasound wave is sent through the metal and is reflected back from the crack to the detector in 0.01 ms?

[ ]	0.025 m
[ ]	50 m
[ ]	50 cm
[ ]	25 cm

Which of the following is/are advantages of ultrasound used in medical scanning?

[ ]	Non invasive - it is all done from the outside of the body
[ ]	Inexpensive compared to other scanning methods
[ ]	It is non-ionising
[ ]	All of the above

Which of the following is/are disadvantages of ultrasound?

[ ]	Limited resolution
[ ]	Reflected strongly when passing from tissue to gas
[ ]	Does not pass well through bone
[ ]	All of the above

Which of the following statements is correct?

[ ]	Ultrasound waves are partially reflected when they are incident upon a boundary between two different mediums. The time it takes for the reflections to hit a detector can be used to determine the distance the boundary is from the detector
[ ]	Ultrasound waves are fully reflected when they are incident upon a boundary between two different mediums. The time it takes for the reflections to hit a detector can be used to determine the distance the boundary is from the detector
[ ]	Ultrasound waves are partially reflected when they are incident upon a boundary between two identical mediums. The time it takes for the reflections to hit a detector can be used to determine the distance the boundary is from the detector
[ ]	Ultrasound waves are fully reflected when they are incident upon a boundary between two identical mediums. The time it takes for the reflections to hit a detector can be used to determine the distance the boundary is from the detector

10.

Which of the following are medical uses of ultrasound?

[ ]	Pre-natal screening
[ ]	Breaking down kidney stones
[ ]	Neither of the above, X-rays are used
[ ]	Both of the above

Physics Quiz - Medical Physics - Ultrasound (Answers)

What is the frequency above which a sound wave is known as ultrasound?

[ ]	5,000 Hz
[ ]	10,000 Hz
[ ]	15,000 Hz
[x]	20,000 Hz

This frequency is above the limit at which the human ear can hear, however many other animals can hear it easily

Which of the following can be a use of ultrasound waves?

[ ]	Sonar
[ ]	Animal communication
[ ]	Foetal scanning
[x]	All of the above

Ultrasound is not just useful in medical applications

Which formula correctly relates speed, distance and time?

[ ]	Speed = Distance x time
[ ]	Distance = ^Time/_speed
[x]	Speed = ^Distance/_Time
[ ]	Speed = ^Time/_Distance

This equation is used by medical ultrasound scanners to build up an image

[ ]	350 m
[x]	375 m
[ ]	500 m
[ ]	675 m

This is an example of a non-medical use that you need to know for the GCSE. We can use ultrasound to determine depths and distances to underwater obstructions or to detect other vessels

The speed of ultrasound in air is 330 m/s. How far away is a car if an ultrasound wave is sent to it along a road and takes 0.1 s to return?

[ ]	10 m
[ ]	14.5 m
[x]	16.5 m
[ ]	20 m

distance = speed x time so the answer to this calculation is 330 x 0.05 m. When dealing with echoes, remember that you will often need to half the time otherwise you will be calculating the distance of the journey of the sound there and back

The speed of ultrasound in metal is 5,000 m/s. How far away is a crack in the metal if an ultrasound wave is sent through the metal and is reflected back from the crack to the detector in 0.01 ms?

[x]	0.025 m
[ ]	50 m
[ ]	50 cm
[ ]	25 cm

Such short time periods can only be measured electronically

Which of the following is/are advantages of ultrasound used in medical scanning?

[ ]	Non invasive - it is all done from the outside of the body
[ ]	Inexpensive compared to other scanning methods
[ ]	It is non-ionising
[x]	All of the above

It is safe enough to use to scan a foetus in the womb to check on its progress

Which of the following is/are disadvantages of ultrasound?

[ ]	Limited resolution
[ ]	Reflected strongly when passing from tissue to gas
[ ]	Does not pass well through bone
[x]	All of the above

Whilst ultrasound has some disadvantages such as those listed above, the advantages far outweigh them for the applications for which they are used. Using a non-invasive imaging technique for delicate medical issues such as foetal scanning is much more preferred than an intrusive procedure which could cause unnecessary complications