P3.1 Flashcards
Difference between ultrasound waves and xrays
Ultrasound waves are non-ionising and X-rays are ionising
Properties of X-rays
They affect a photographic film the same way as light
They are absorbed by metal and bone
They are transmitted by soft tissue
Their wavelength is of the same order of magnitude as the diameter of an atom
What spectrum are X-rays a part of
Electromagnetic spectrum
Are X-rays wavelength short or long
Short
What do xrays cause
Ionisation
What 5things can X-rays be used for
Diagnose and treat medical conditions CT scans Killing cancer cells Bone fractures Dental problems
What does the use of charge-coupled devices(CCDs) allow
Images to be formed electronically
What needs to be taken when X-rays and CT scanners are in use
Precautions
What is the range for human hearing
200 to 20,000 Hz
What can electronic systems to produce
Ultrasound waves
What frequency do ultrasound waves have
A frequency higher than the upper limit of hearing for humans
When are ultrasound waves partially reflected
When they meet a boundary between two different media
What can the taken for the reflections to reach a detector be used to determine
How far away such a boundary is
What can ultrasound be used in and for what
In medicine
Pre natal scanning
Removal of kidney stones
What is refraction
The change of direction of light as it passes from one medium to another
How does a lens form an image
Refracting light
What happens in convex or converging lens
Parallel rays of light are brought to a focus at the principal focus
What is the focal length
The distance from the lens to the principal focus
How is the nature of an image defined by
Its size relative to the object
Whether it is upright or inverted relative to the object
Whether it is real or virtual
What is a use of converging lens
Magnifying glass
What is in a eye
Retina Lens Cornea Pupil/ iris Ciliary muscle Suspensory ligaments
What is being long sighted caused by
The eyeball is too short or the eye lens being unable to focus
What is being short sighted caused by
The eyeball being to long or the eye lens being unable to focus
What is the range of vision
Between the near point and the far point
The length of the near point
25cm
The length of the far point
Infinity
What is equivalent to the retina in the eye
The film in a camera or the CCDs in a digital camera
The power of what is positive
The power of a converging lens
The power of what is negative
The power of a diverging lens
What is the focal length determined by
The refractive index of the material from which the lens is made
The curvature of the two surfaces of the lens
For a given focal length, the greater the refractive index…… and what does it means
The flatter the length
It means that the lens can be manufactured thinner
Examples of the use for visible light
Endoscope for internal imaging
What can visible light be sent along
Optical fibres
What are lasers
Qn energy source for cutting, cauterising, burning and eye surgery
