Topic 5 - Light and the EM spectrum

Question 1

Explain why total internal reflection occurs

Answer 1

Total Internal Reflection occurs when the angle of incidence is greater than the critical angle

Question 2

What happens to a ray of light when it passes from air to glass?

Answer 2

It slows down because light slows down when it enters a denser medium

Question 3

How are optical fibres used in endoscopes?

Answer 3

Optical fibres bend, some carry light to the inside of the patient and some transmit the reflected light. The light passes up/down the fibres via total internal reflection, the light is reflected inside the patient and produces an image the computer can analyse

Question 4

Explain 3 ways ultrasound can be used as a medical treatment for illness or injury

Answer 4

It can break kidney stones, Energy absorbed can help repair damaged muscle tissue, the use of it as a gel can prevent loss of intensity

Question 5

Give 5 advantages of using a camera rather than the naked eye for studying stars

Answer 5

Measurements can be taken, there is a permanent record, the image can be magnified, the camera can detect waves outside of the visible light part of the spectrum and after long exposure they can see faint objects and track objects

Question 6

How did Galileo’s observations of Jupiter’s moons change scientists’ ideas about the universe?

Answer 6

It led to people stopping believing the geocentric model as the moons were orbiting Jupiter, not Earth and meant that the heliocentric model was preferred

Question 7

What is the equation for the linear magnification of a thin lens in cameras and what does each letter mean?

Answer 7

M=f/d-f
M = The linear magnification of a thin lens
F = The focal length of the lens
D = The distance between lens and object

Question 8

What is the linear magnification of a thin lens when the focal length is 12 and the distance is 14?

Answer 8

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