PHY 11 - Light and Geometrical Optics Flashcards Preview

GAMSAT March 2016 > PHY 11 - Light and Geometrical Optics > Flashcards

Flashcards in PHY 11 - Light and Geometrical Optics Deck (27)
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1
Q

What is the approximate speed of light in a vacuum ?

A

295 000 000 m/s

2
Q

What is refraction of light dependent on ?

A

The density of the medium

e.g. water = low density and therefore minimum refraction

3
Q

What is meant by the rarer medium in terms of light ?

A

The least dense medium

4
Q

What happens to light when it passes from a rarer to a denser medium ?

A

It is refracted towards the normal (90º to the surface)

5
Q

What happens to light when it passes from a denser to a rarer medium ?

A

It is refracted away from the normal (90º to the surface)

6
Q

What is the difference between the angle of incidence and the angle of refraction ?

A

They are equal

7
Q

Why do we see colour ?

A

Different wavelengths of light make up the visible portion of the light spectrum (the electro-magnetic spectrum)

8
Q

Describe the two aspects of the theory of light

A
  1. Particulate - referring to a packet of energy called a photon e.g. used to describe the photoelectric effect
  2. Wavy - e.g. light interference and diffraction
9
Q

Why does diffraction occur ?

A

When waves of light bend at the interface between two different media.

10
Q

Describe the optical domain of the electromagnetic wave theory ?

A

It corresponds to the following range of wavelengths:

0.4µ< h (visible) < 0.8µ

(µ = microns = 10-6 metres)

11
Q

What is an electromagnetic field ?

A

At every point of the field there are two perpendicular vectors:

E: Electrical field vector

B: Magnetic induction field vector

12
Q

What is polarized light ?

A

The electromagnetic wave front is polarized in a straight line when E and B are fixed at all times.

Therefore, it is light that has waves in only 1 plane.

13
Q

What is reflection in terms of light ?

A

The process by which light rays bounce back into a medium from a surface with another medium.

14
Q

What is the difference between an incident and a refracted ray ?

A

The ray that arrives from the source is the incident ray, the reflected ray is the ray that bounces back

15
Q

What are the laws of reflection ?

A

The angle of incidence equals the angle of reflection at normal.

16
Q

What are spherical mirrors ?

A

They are non-plane mirrors which may have the reflecting surface concave (converges light) or convex (diverges light)

17
Q

What is a vertex ?

A

The centre of a mirror

18
Q

Describe the convention for lower and upper case letters in terms of light optics

A

Upper case: refer to a point

Lower case: refer to a distance

19
Q

What is refraction ?

A

The bending of light as it passes from one transparent medium to another. This is caused by the different speeds of light in the two media

20
Q

What is the relationship between wavelength and speed ?

A

Longer wavelengths travel faster in a medium than shorter wavelengths (ie. longer wavelengths are more subject to refraction)

21
Q

What is dispersion of light ?

A

The separation of white light (ie. all colours together) into individual colours by differential refraction

22
Q

What are the laws of refraction ?

A
  1. The incident ray, the refracted ray and the normal ray all lie in the same plane
  2. The path of the ray (incident and refracted parts) is reversible
23
Q

What is the critical angle in terms of light optics ?

A
24
Q

Explain why when looking at an object under water from above the surface, the object appears closer than it actually is ?

A
25
Q

What is a lens ?

A

A transparent material which refracts light

26
Q

What is the difference between converging and diverging lenses ?

A

Converging lenses refract toward the axis, diverging lenses refract away from the axis.

27
Q

What are aberrations in terms of light optics ?

A

E.g. A nick or a cut in a convex lens might create a microscopic are of concavity, causing divergent light instead of convergent light. The image will be less sharp or clear as the number or sizes of aberrations increase.