Light Waves

Question 1

Angle of incidence = ?

Answer 1

Angle of reflection

Question 2

when light hits a mirror, it must pass through the?

Answer 2

focal point/focus

Question 3

concave mirror towards or away from focal point?

Answer 3

towards focal point

Question 4

define refraction

Answer 4

refraction is the change in speed of a wave in a different medium

Question 5

when a wave bends, is that refraction?

Answer 5

no, it is a sign of refraction, which means speed of wave and subsequently, wavelength have changed

Question 6

when a wave enters a denser medium, what occurs?

Answer 6

wavelength decreases, and from v = f*lambda, velocity decreases

Question 7

when a wave enters a less dense medium, what occurs?

Answer 7

wavelength increases, velocity increases

Question 8

when a wave enters a medium, what remains constant?

Answer 8

frequency remains constant

Question 9

when a wave (non parallel to the surface) enters a denser medium, does it bend towards or away from the normal?

Answer 9

towards the normal for denser mediums

Question 10

when a wave (non parallel to the surface) enters a less dense medium, does it bend towards or away from the normal?

Answer 10

away from the normal for less dense mediums

Question 11

Snell’s law is?

Answer 11

sinx1 / sinx2 = v1 / v2 = n2 / n1

Question 12

snell’s law for angles and refractive index only

Answer 12

sinx1n1 = sinx2n2

Question 13

why can’t a refractive index be <1

Answer 13

because nothing can travel faster than the speed of light

Question 14

what is the critical angle

Answer 14

the critical angle is the angle of which a wave refracts along the surface that it touches, (parallel)

Question 15

what happens if the angle of incidence is greater than the critical angle?

Answer 15

total internal reflection occurs. (total internal reflection can only occur from Dense to less dense)

Question 16

provide an example of the use of TIR

Answer 16

optical fibres (NBN) use total internal reflection to carry digital data in the form of light

Question 17

what is cladding

Answer 17

use of less dense mediums to prevent light from escaping via reflection

Question 18

describe constructive interference

Answer 18

when waves are in the same phase (pattern) and essentially increase the strength by becoming a single wave

Question 19

describe destructive interference

Answer 19

when waves out of phase cancel each other out

Question 20

describe superposition

Answer 20

when one wave is placed on top of another, and the wave changes

Question 21

what is the virtual image

Answer 21

image that appears on the opposite side of the mirror