Light and Colour

Question 1

What is total internal reflection?

Answer 1

• When light is completely reflected back at a boundary between two mediums.
• It occurs when light meets a less dense medium at an angle of incidence larger than the critical angle.

Question 2

What is the critical angle?

Answer 2

The angle of incidence which causes the angle of reflection to be 90 degrees.

Question 3

What determines the colour of visible light waves?

Answer 3

The wavelength of frequency of the light waves

Question 4

What colour of visible light has the highest frequency?

Answer 4

Blue

Question 5

What colour of visible light has the largest wavelength?

Answer 5

Red

Question 6

What is meant by the term ‘specular reflection’?

Answer 6

Rays are reflected from a smooth surface in a single direction

Question 7

What is meant by the term ‘diffuse reflection’?

Answer 7

Reflection from a rough surface which causes scattering

Question 8

How does a red colour filter work?

Answer 8

• A red filter absorbs all wavelengths of light other than those in the red range of the spectrum.
• This means only red light passes through the filter

Question 9

What is meant by “opaque”?

Answer 9

Not see-through

Question 10

What governs the colour of an opaque object?

Answer 10

• Different objects reflect different wavelengths of light by different amounts
• The wavelength that are most strongly reflected determine the colour

Question 11

What happens to the wavelengths of light that aren’t reflected by an opaque object?

Answer 11

Any wavelengths that aren’t reflected are absorbed by the object

Question 12

What colour does an object appear if all wavelengths are reflected by equal amounts?

Answer 12

White

Question 13

What colour does an object appear if all wavelengths are absorbed?

Answer 13

Black