Chapter 1d

Question 1

Snells law to find refraction

Answer 1

N1sin(01)=n2sin(02)
N1v1=n2v2

Question 2

What is the tir and critical angle formula including applications

Answer 2

N1sin(0c)=n2sin(90)

Question 3

What does sin (90) equal

Answer 3

1

Question 4

Angle of incident v angle of refraction v angle of reflection

Answer 4

angle of incidence the angle to the normal of a ray approaching a medium boundary
angle of reflection the angle to the normal of a ray reflected at a medium boundary
angle of refraction the angle to the normal of a ray refracted at a medium boundary

Question 5

Critical angle meaning

Answer 5

the angle above which total internal reflection occurs

Question 6

Normal meaning

Answer 6

an imaginary line perpendicular to the medium boundary at the point of incidence

Question 7

Refraction meaning

Answer 7

the change in direction of a wave moving between two mediums with different refractive indices

Question 8

Refractive index meaning

Answer 8

for a given medium, the ratio of the speed of light in a vacuum to the speed of light in that medium

Question 9

Total internal reflection TiR meaning

Answer 9

the reflection of all incident light at a boundary between two mediums

Question 10

Transmission meaning

Answer 10

the transfer of wave energy through or between wave mediums

Question 11

Critical index equation

Answer 11

n = c/v

Question 12

Refractive index and wave speed equation

Answer 12

N1v1=n2v2

Question 13

Wave equation (frequency)

Answer 13

V= f times wavelength

Question 14

Refraction explanation

Answer 14

When light crosses boundaries to another medium it can change speed and direction. Causing it to refract. Refractive index is the speed of light through a given vacuum. The grate the index the slower light moves in the medium,

Refraction can cause rainbows and mirages

Question 15

How is the refractive index of a medium determined

Answer 15

The speed of light in a medium will depend on the physical characteristics of the medium (including temperature, density, and type of material) and the frequency of the light. The refractive index, n, is found from the ratio between the speed of light in a vacuum, c, and the speed of light in that medium, v.
N= c divide v

Question 16

Refractive index facts

Answer 16

Minimum is 1
Air is 1
Water is slower so it’s close to 1.33

Question 17

Find how many times faster light travels through water then glass

Answer 17

Speed of light in water divide speed of light in glass

Question 18

How does light behave at boundaries between mediums

Answer 18

How light moves as it changes between mediums depends on the refractive indices of those mediums as well as the angle that it arrives at the boundary between them. We use the refractive indices and the angle it arrives at the boundary to predict:

which direction the light will move in, • at what angle the light will deviate.

Whenever light hits a boundary between two mediums, some of the light will reflect back into the medium it is travelling in as shown in Figure 2. Light that is transmitted from one medium into another may refract (change direction). This is caused by light slowing down or speeding up as it travels between the mediums

The angles of incidence (θ ), reflection (θ ), and refraction (θ ), are always
measured between the relevant ray of light and the normal. Light will always be reflected at the same angle to the normal as it was incident (θ = θ ).
The amount and direction light will refract depends on th e ratio between the refractive indicies of the tow mediums.

Question 19

Misconception If the incident light travels in the direction normal to the boundary, crossing the boundary will have no effect on it.’

Answer 19

Light crossing the boundary at an angle of incidence of 0° means that
it will not change direction, however its speed (and therefore its wavelength) will still be affected by changing medium. When passing between mediums, the frequency of light
will be unchanged.

Question 20

How light reacts travelling through mediums

Answer 20

When light travels from its current medium into one with a higher refractive index, as in Figure 3(a), it:
• bends towards the normal,
• therefore the angle of refraction θ will be less than the angle of incidence θ .
When light travels from its current medium into one with a lower refractive index, as in Figure 3(b), it:
ri
• bends away from the normal, KEEN TO INVESTIGATE?
• therefore the angle of refraction θ will be greater than the angle of incidence θ ​.

Question 21

Snells law facts

Answer 21

Snells law give a formula for light passing between mediums relating the refractive indices of each medium with the angle of incidence and angle of refraction.
We use Snell’s Law to calculate the direction light, compared to the normal, will move after travelling through the boundary between mediums. Snell’s Law has a wide range of applications in optics, the branch of physics that studies the behaviour of light, helping construct cameras, eyeglasses and contact lenses.
Theory and applications
The angle of refraction is related to the incident angle and the refractive indices
of the boundary medium by Snell’s Law. The relationship between these four values

Question 22

Who uses snells law and why

Answer 22

Optometrists, to calculate shape and thickness of lense to change the direction of incoming light so that the eye refracts the rays to focus exactly on the retina

Question 23

Total internal reflection and critical angle connection

Answer 23

Total internal reflection and critical angle 1.1.7.3
The critical angle is the incident angle at which the refracted angle is 90°. Light with an incident angle greater then the critical angle will be totally internally reflected. It is possible for light to be refracted at a 90 degree angle away from the normal, or even for it to become impossible for light to be transmitted through a boundary. These phenomena, critical angle and total internal reflection, allow for gemstones to sparkle and for the construction of edge-lit LED panels.

Question 24

Why does the critical only exit sometimes and how is it determined

Answer 24

When light hits a boundary between the medium it is travelling through and one with a lower refractive index, it bends away from the normal (provided θ ≠ 0°).
is it determined?
As a result, the angle of incidence can be increased to a point where the angle of refraction reaches 90°. The incident angle at which this occurs is called the critical angle, and is depicted in Figure 7.

The critical angle exists when light hits a boundary to a medium with a lower refractive index. If it reaches a boundary between its current medium and one with a higher refractive index then the refracted ray would bend towards the normal, and so the angle of refraction cannot reach 90° since θ > θ .
Figure 7 Formation of a critical angle
To find the critical angle θ using Snell’s Law, we assume that θ = θ and θ = 90°. c 1c2
Since sin(90° ) = 1.00, Snell’s Law can be rewritten to find the critical angle

Question 25

How snells law is rearranged to find the critical angle

Answer 25

n 1 sin(θ c ) = n 2
Rearranged:
0c= sin ^-1(n2/n1)

Question 26

Total internal reflection happens because light is refracted into its initial medium.’
Misconception

Answer 26

Total internal reflection occurs because at angles greater than the critical angle, it is impossible for light to transmit and refract into the other medium, and so all light is reflected..

Question 27

Why does total internal reflection occur and how is it used

Answer 27

If the angle of incident is greater then the critical angle, then the angle of refraction will be greater than 90°, so the light cannot be transmitted and will remain in its initial medium. This is known as total internal reflection, and is shown

Total internal reflection is also used to light LED lights. QLight is shone into a thin glass panel at an angle such that it will totally internally reflect off the inside surfaces, and only leave the panel through the edges or through a design etched on the surface. This way the panel glows only in certain parts, and appears transparent in others. Also used with gems and cutting them so they are totally internally reflected before leaving the gem.