Medical Physics S2 Flashcards
What is sound?
A form of energy transferred as a wave through solids, liquids and gases9
How fast does sound travel through air?
Sound travels at 340 metres per second in air
What is sound caused by?
Vibrations
What is the frequency?
Number of vibrations in one second is called the frequency of the sound, its measured in hertz (Hz)
What frequency do high-pitched sounds have?
High frequency
What frequency do low-pitched sounds have?
Low frequency
What Hz can humans hear between?
20 to 20,000 Hz
What are vibrations over 20,000 called?
An ultrasound
What is the volume?
The size of waves in Hz
What is sound level measured in?
Decibels (dB)
What decibels damages your ears?
Anything above 90 dB can damage your ears
What is light?
Light is a form of energy transferred as a wave
Can light pass through a vaccum?
Yes
How fast does light travel?
300 million metres per sec
How does light travel?
In straight lines
How can you change the direction of light?
If its reflected or refracted
Lenses only work because..?
of refraction
What do convex lenses do?
Cause light to converge (come together)
What do concave lenses do?
Cause light to diverge (move apart)
How do your eyes send messages to your brain?
Eyes convert light into electrical signals interpreted by the brain
What are the main parts of the eye?
Cornea; pupil; iris; lens; retina; and optic nerve
What do long-sighted people see?
They see distant objects clearly but close objects are blurred
How do you fix long-sighted?
Convex lenses
What do short-sighted people see?
They see close objects clearly but distant objects are blurred
How do you fix short-sighted?
Concave lenses
What is white light made up of?
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 the human eye
Whats on the EM spectrum?
Radio/TV; Microwave; Infrared (IR); Visible light; Ultraviolet (UV); X-rays; Gamma rays;
What is Infrared (IR)?
Heat energy
What is Ultraviolet (UV)?
From the sun, causes sun burn and skin cancer
What are X-rays?
Can penetrate the body, can be dangerous
What are Gamma-rays?
Can be dangerous
What is medical imaging?
Different waves used to give medical information
What is an Ultrasound?
- Sound waves reflect off bony material
- Used to examine babies in the womb
- Can monitor blood flow
How is Infrared used in medicine?
- Measure body temperature
- can show tumours and arthritis
How is UV used in medicine?
Detecting skin conditions
How are X-rays used in medicine?
- Internal images
- energy absorbed by bony material
- used to examine breaks and fractures
What is a CAT (Computed Axial Tomography) scanner do in medicine?
- 3-dimensional X-ray images of the whole body
What does a MRI (Magnetic Resonance Imaging) scanner do in medicine?
- 3-dimensional images of the soft tissue of the whole
- good for brain images
What does Ultrasound treat?
They can break up kidney stones
What does an IR treat?
Sports injuries
What does UV treat?
Skin conditions
What does X-ray treat?
It kills cancer cells
