TOPIC THREE-Waves and optics

define refraction

the bending of light when it changes medium

Why does refraction happen

When a wave enters a denser medium, it slows down (and vice versa). when the light enters, it will change direction.

What is the trend with denser materials in terms of refraction and speed

The denser a material, the slower light travels, and the more “bending” we see.

Which direction does he light bend when entering a more dense material

Bends towards the normal and slows down

Which direction does he light bend when exiting a more dense material

light bends away from the normal and speeds up

what type of lens do we focus on in physics

biconvex

lens diagram

is a thicker or thinner lens more powerful?

thicker is more powerful as the focal point is closer

thin lens diagram

thick lens

what assumptions do we need to make about convex lenses

there is only one change in direction for each light ray as it passes through the lens.

rays that pass through the centre are undeviated

what is a real image

Image is opposite side to the object

what is a virtual image

image is same side as object

what is an upright image

Image is pointing same way as object

What is an inverted image

image is pointing opposite way to object

What is a magnified image

image is bigger than object

What is a reduced image

image is smaller than object

How do you draw a graph of a light ray passing through a convex lens

Draw a straight line from the object to the lens, parallel with the principal axis. Then draw a straight line from the object through the centre of the lens and out the other side. Then, from the end of the first line, draw another line going through the focal point and out the other side. Wherever the two lines meet is where the image forms

what is the critical angle

the specific angle of incidence when no light leaving a denser material will escape the block. The light is either diverted along the boundary or reflected back inside the glass.

What is total internal reflection

When all light is reflected back inside the more dense material when it is leaving.

fibre optics TIR diagram

What is amplitude

Maximum distance from rest

What is wavelength

Distance between two consecutive, identical points in a wave cycle

What is frequency

The number of wave cycles per second

What is time period

Time taken for one wave cycle

What is the difference between a transverse and longitudinal wave

The direction of energy transfer. In a longitudinal wave, the direction of oscillation is parallel to the direction of energy transfer.

In a transverse wave, the direction of oscillation is perpendicular to the direction of energy transfer

What is a specular reflection

Image formed when light reflects of a smooth surface.

What is a diffuse reflection

no image formed when light scatters off a bumpy surface