End Of Unit Questions Flashcards
What is a CT scanner?
A device that uses X-Rays to produce digital images of a cross section through a body
What is an ultrasound wave?
A sound wave with a frequency greater than 20,000Hz, above human hearing
Why are X-Rays not used for prenatal scans?
X-Rays are ionising so could harm the unborn baby
A Ray of light travels through the glass of refractive index of 1.54, the angle of incidence is 15*, what is the angle of refraction?
9.7*
What happens to a Ray of light that enters the glass block along the normal?
It passes into the block without changing direction
A Ray of light strikes the boundary between glass and air at the critical angle. What will happen to the Ray?
It will be refracted at 90* along the boundary
What is the principal focus of a diverging lens?
The point that parallel rays of light appear to have diverged from after they have passed though the lens
Describe the image formed by a diverging lens?
Virtual, upright, diminished
What are the ciliary muscles?
Muscles that control the thickness of the lens in the eye
What is the power of a lens of focal length 16cm?
6.25d
A lens used as a magnifying glass produces a magnification of 6. If the height of the images is 9cm, what is the height of the object?
1.5cm
Why do workers in hospital X-Ray departments wear film badges?
To monitor the exposure to X-Rays
