Light and Sound (Reflection/Refraction/TIR)

Question 1

what does ‘i’ stand for

Answer 1

angle of incidence

Question 2

what does ‘r’ stand for in reflection?

Answer 2

angle of reflections

Question 3

what does the law of reflections say?

Answer 3

i=r

Question 4

how can we see?

Answer 4

light from the sun and light bulbs reflect off every surface

Question 5

what happens when i=0?

Answer 5

the light doesn’t change direction

Question 6

define refraction

Answer 6

the change in direction of a wave as it changes speed

Question 7

define reflection

Answer 7

the return of light or sound waves from a surface

Question 8

what is the normal?

Answer 8

a dotted line drawn perpendicular to the surface of the refracting material

Question 9

what is a wavefront?

Answer 9

lines along the crest of a wave

Question 10

rays and wavefronts are always at what angle?

Answer 10

90 degrees

Question 11

reflection does not change the…

Answer 11

wavelength (lambda)

Question 12

in deep water waves travel… but in shallow water they travel…

Answer 12

faster - slower

Question 13

if i=0…

Answer 13

there is no change in direction

Question 14

if i=/ 0…

Answer 14

water waves refract towards the normal

Question 15

what does ‘r’ stand for in refraction?

Answer 15

angle of refraction

Question 16

when does wavelength always change?

Answer 16

in refraction

Question 17

why does the ray change direction in the water?

Answer 17

one side (X) slows down before the other side (Y) (a bit like slowing the left-hand side of a sledge and using the left foot causing it to turn left)

Question 18

refraction doesn’t change the…

Answer 18

frequency

Question 19

what is one thing that doesn’t change in refraction?

Answer 19

the frequency

Question 20

lenses are found in:

Answer 20

cameras, eyes, telescopes, microscopes

Question 21

what is the wave equation?

Answer 21

v = f * λ

Question 22

how does light travel?

Answer 22

in a straight line

Question 23

what is an example of refraction?

Answer 23

shallow writing- writing appears to be higher

Question 24

in these optical illusions causes by refraction…

Answer 24

1. light speeds up as it leaves the water/glass
2. it refracts from the normal
3. its assumes light travels in a straight line so we see a virtual image

Question 25

what does TIR stand for?

Answer 25

Total Internal Reflection

Question 26

when does TIR happen?

Answer 26

1. moving from a slow medium to a fast-medium

2. when the angle of incidence is greater than the critical angle (i>c)

Question 27

what is a medium?

Answer 27

a substance or material that carries the wave

Question 28

what is the critical angle?

Answer 28

the angle of incidence is called the critical angle

Question 29

what is a fast-medium?

Answer 29

air/vacuum

Question 30

does the critical angle change?

Answer 30

the critical angle varies depending to the material used

Question 31

how does TIR work?

Answer 31

when the ray is greater than the critical angle, the ray will reflect
but if the ray is less the critical angle, the ray will refract through the medium ( i=r ; angle of incidence and reflection are the same)

Question 32

what is the critical angle for glass?

Answer 32

42 degrees

Question 33

TIR happens when…

Answer 33

i = r

Question 34

where is the normal?

Answer 34

90 degrees from the medium’s line

Question 35

name 3 examples TIR can be found in

Answer 35

1. a periscope
2. bike reflector
3. communication cables around the world