Medical Physics Flashcards
(40 cards)
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.
