Physics Quiz Final- Refraction- Gr10- SNC2D1

How does light travel?

In straight lines

What is special about light rays?

That light rays can reflect and refract causing the direction of light to change

What is refraction?

Lights change in direction when it passes at an angle from one medium into another medium

What is refraction the crossing of?

The crossing of a boundary between to mediums

What is a medium?

The material that light moves through

What does the speed of light do in different mediums?

The speed of light changes depending on which medium its travelling through

What is the speed of light in a few important mediums?

Vacuum- 3.00x10^8m/s, Water- 2.26x10^8m/s, Acrylic- 1.76x10^8m/s

When does refraction occur?

It occurs when the speed of light changes in different mediums

What do the particles in a medium do which causes the speed to change?

The particles in a medium slow down the passage of light waves and different mediums slow light down by different amounts

Where does light refract?

Light only refracts at the boundary when it is entering or leaving a medium

What causes more light to be refracted?

The more that light shows down while entering a medium the more light is refracted

What is a refracted ray?

The ray that is formed after crossing a boundary between mediums

What is the angle of refraction?

The angle between the refracted ray and the normal

What are the rules of refraction? 1/3

1- The angle of refraction is measured relative to the normal

What are the rules of refraction? 2/3

2- The light bends towards the normal when the speed of light in the second medium is slower than the speed of the first medium

What are the rules of refraction? 3/3

3- Light bends away from the normal when the speed of light in the second medium is faster than the speed of light in the first medium

What is thickness known as and how does it affect how light travels?

Thickness is known as optical density (IOR) and the thicker the medium, the slower the light travels

What is the index of refraction?

The amount by which a transparent medium decreases the speed of light

What is the formula to measure index of refraction?

N= c/v in which c=the speed of light in a vacuum, and v= the speed of light in a unspecified medium

What is dispersion?

The process of separating colours by refraction

What is special about each colour?

That each colour of light travels at a slight different speed in a different medium

Which colour travels the slowest and fastest?

Violet travels the slowest and bends towards the normal, while red is the fastest and bends away from the normal

What is partial reflection/partial refraction?

Refraction and reflection can occur simultaneously when light passes through different medium causes some light to refract and reflect

Whats a key part of partial reflection/refraction?

Both reflection and refraction do occur but not equally, the amount of each depends on the angle of incidence

How do you determine wether more is being refracted or reflected?

If the angle of incidence decreases (is smaller) more light will refract instead of reflect, if the angle of incidence increases (is bigger) more light will reflect and less will refract

What happens if the angle of incidence increases many times?

As the angle of incidence increases the angle of refraction increases to the maximum of 90° causing no refraction to occur

What causes the angle of refraction to hit 90°?

When light travels from a slower to a faster medium there is an angle of incidence that can cause the angle of refraction to hit 90°

What is the critical angle?

The particular angle of incidence that causes there to be no refraction (the angle of refraction becomes maxed out at a certain value)

Angle of incident compared to critical angle 1/3

1- If the angle of incidence is less then the critical angle the light will refract away from the normal (in a slower to faster medium)

Angle of incident compared to critical angle 2/3

2- If the angle of incidence is equal to the critical angle the angle of refraction is 90° and travels along the boundary (in a slow to faster medium)

Angle of incident compared to critical angle 3/3

3-If the angle of incidence is greater than the critical angle then all the light is trapped inside the slower medium and reflects instead of refracting

What is total internal reflection?

The phenomenon that occurs when the angle of incidence is greater than the critical angle

What are the two conditions needed for total internal reflection to occur?

1- Light must be travelling from a slow to fast medium, 2-The angle if incidence must be greater than the critical angle

How do you calculate a critical angle?

Sin O1= n2 sin O2
——————————-
n1

What is the relation between IOR and the critical angle?

If the IOR is high then the critical angle is low, and if the IOR is low then the critical angle is high

What are 3 applications of total internal reflection?

Diamonds, Fibre Optics, and Retroreflectors

What are the characteristics of diamonds?

Diamonds sparkle due to total internal reflection, they have a low critical angle are the cut of the diamond makes it sparkle more

What are fibre optics?

Light transmitted info along glass or plastic cable. It has a small critical angle and will always have an angle of incidence greater than the critical angle so light can stay inside the cable

What are retroreflectors?

A retroreflector is a device that reflects light back towards the original source of light

What is apparent depth?

The depth that an object in water appears to be shallow due to the refraction of light (objects appear closer then they actually are)

Why does apparent depth happen?

It happens since your brain projects light rays backwards in a straight line to create a virtual image in the water

What is a mirage?

A virtual image of the sky

Why do mirages happen?

They happen since light travels slow in cold air and faster in hot air causing light to bend away from the normal which causes images from the sky to appear in-front of us on the ground

What is a lens?

A transparent object with a one side curve that refract light since they have no opaque surface

What are the two types of lenses?

Converging and diverging

What are convering lenses

Parallel light rays that converge to a single point (focal) after refracting through the lens

What are the characteristics of a converging lens?

The converging lens is thickest in the middle and is also called bioconvex

What are diverging lenses?

Parallel light rays that diverge (spread apart) after refracting through the lens

What are characteristics of diverging lenses?

They are the thinnest in the middle and is called a concave lens

What is the centre of a lens called?

The optical centre

What two focal points do lenses have?

F and F' where F is the principal focus and F' is the secondary principal focus

Where do virtual images appear in lenses?

On the same side as the object not the other side

What is the main difference of the principal focuses between diverging and converging lenses?

In converging lenses the F is located on the left side and the F' is located on the right where in diverging the F is on the right and the F' is on the left