Medical Physics Flashcards
What is sound?
A form of energy transferred as a wave through solids, liquids, and gases.
How fast does sound travel?
Sound travels at 340 metres per second in air.
What causes sound?
Sound is caused by vibrations.
What is the number of vibrations in 1 second called and what it is measured in?
Number of vibrations in one second is called the frequency of the sound. It is measured in
hertz (Hz).
What frequency do high-pitch and low-pitch sounds have?
High pitched sounds have high frequency. Low pitched sounds have low frequency.
What can humans hear up to?
Between 20Hz to 20,000Hz
?? dB damages hearing
?? - 90 dB
Changing the frequency of a sound changes the what?
the pitch
Higher amplitude of a sound looks like?
waves with a greater amplitude (they are taller)
Higher frequency of a sound looks like?
More waves
What is ultrasound?
Vibrations above 20,000Hz are called an ultrasound.
What can an ultrasound be used for?
Breaking up kidney stones, create images of inside body and can detect blood flow.
How does an ultrasound work?
they bounce off different parts of the body, they create “echoes” that are picked up by the probe and turned into a moving image.
What is sound level measured in?
Decibels (dB)
What is light?
A form of energy transferred as a wave.
How fast does light travel?
Light travels at 300 million metres per second.
What can light pass through?
A vaccuum
What direction does light travel in?
Light travels in straight lines. Direction only changes if it is reflected or refracted.
What are the 2 types of lenses? and how do they work?
Lenses work due to refraction.
Convex lenses cause light to converge (come together). Concave lenses cause light to diverge (move apart).
Main parts of the eye:
cornea; pupil; iris; lens; retina; and optic nerve.
The eye does what to light?
Eye converts light to electrical signals interpreted by the brain.
What do long sighted people see and what corrects it?
Long-sighted people can see distant objects clearly but close objects are blurred. Corrected by convex lens.
What do short sighted people see and what corrects it?
Short-sighted people can see close objects clearly but distant objects are blurred. Corrected by concave lens.
What is white light made up of?
different colours – ROYGBIV the rainbow
spectrum.
What are laser beams?
LASER beams are very narrow beams of light energy of a single
colour.
What is the EM spectrum?
Family of waves similar to light but invisible to human eyes.
What is on the EM spectrum?
● TV/Radio
● Microwave
● Infrared (IR)
● Visible light
● Ultraviolet (UV)
● X-rays
● Gamma rays
Order of lowest frequency to highest:
- Radio Waves
- Microwaves
- Infrared Waves,
- Visible Light Rays,
- Ultraviolet,
- X-rays
- Gamma Rays.
What is infrared?
heat energy
what can infrared energy be used for?
In medicine, thermograms can be used to diagnose many conditions and detecting fake bank notes
What is Ultraviolet light?
Ultraviolet energy is produced naturally by the Sun.
What happens if you’re exposed to too much UV?
Too much ultraviolet exposure can cause skin damage.
Large doses of ultraviolet energy can increase our risk of serious conditions like skin cancer
How can you protect yourself from the sun?
Stay in the shadows, or use sun cream.
What are X-rays?
X-ray radiation, is a high-energy electromagnetic radiation
What can X-rays be used for?
In medicine X-rays can be used to diagnose many conditions
How do x-rays work?
The X-rays pass through the body and are absorbed in varying amounts
What do things show up as on X-rays?
Denser material absorbs more X-rays than less dense material
Bone appears as white on an X-ray image, whilst lungs with air in them appear as black. Muscle and fat show up as different shades of grey
What are gamma rays?
Penetrating electromagnetic radiation of a kind arising from the radioactive decay of atomic nuclei.
What can gamma rays be used for?
In the medical field, gamma rays are used in cancer screening devices and in surgical procedures to guide removal of tumors.
How do gamma rays work?
Gamma radiation is highly penetrating and interacts with matter through ionisation via three processes; photoelectric effect, Compton scattering or pair production
