phys:light, electromagnetic spectrum

explain why no light leaves the optical fibre when the light reflects at the boundary between the optical fibre and air.(3)

total internal reflection occurring
angle of incidence is greater than critical
fibre is more dense than air

State why a ray of light does not change direction as it enters a a glass block at a point.(1)

enters along the normal

state what is meant by a virtual image.(1)

image cannot be projected onto a surface

Give one way the magnification of an image could be increased.(1)

use another lens with higher power

the question in the picture

Set up as shown above.
draw around the block mark where ray enters mark where exist
connect
Remove equipment and connect the points

State one example of a use of ultrasound.(1)

baby scanner

State a use of ultrasound.(1)

studying the Earth’s structure

(1)

refraction

The student concludes that angle Y is directly proportional to angle X.

Explain what the student must do to test this conclusion in more detail.(3)

repeat

different angles

for larger angles

When white light crosses the boundary between air and glass, it can split up into the colours of the spectrum. Explain, in terms of speed, why the light behaves like this.(3)

the colours have different wavelengths

different wavelengths

so refract by different amounts