NOT DONE!!!! Chapter #13 - Light

Question 1

What way do light waves travel?

Answer 1

In straight lines.

Question 2

What is the normal?

Answer 2

The normal is drawn 90 degrees to the mirror.

Question 3

What is the incident ray?

Answer 3

A ray of light arriving at the surface.

Question 4

What is reflected ray?

Answer 4

A ray of light which has been reflected from a surface.

Question 5

What is the i angle?

Answer 5

The angle of incidence: The angle between the incident ray and the normal drawn at the point where the ray hits the surface.

Question 6

What is the r angle?

Answer 6

Angle of reflection: The angle between the reflected ray and the normal drawn at the point where the ray hits the surface.

Question 7

What is the law of reflection?

Answer 7

The angle of incidence and the angle if reflection are equal (i=r)

Question 8

Draw a diagram of a mirrior and an object.

Answer 8

Question 9

What type of image is a reflection?

Answer 9

A virtual image

Question 10

What are the properties of an object reflected in a plane mirror?

Answer 10

• The image is the same size as the the object
• The image is the same distance behind the mirror as the object is in front of it.
• it is laterally inverted = left and right are reversed
• It is virtual

Question 11

What is a virtual image?

Answer 11

An image that cannot be formed on a screen

Question 12

When does the ray bend towards the normal?

Answer 12

When the ray enters a denser substance.

Question 13

When does the raybend away form the normal?

Answer 13

When the ray enters a less dense object

Question 14

Why is light refracted?

Answer 14

Because it travles at different speeds in different materials.

Question 15

How do you measure how much light is bent?

Answer 15

By calculating the refractive index.

Question 16

What is the defenition of the refractive index?

Answer 16

The ratio of speeds of a light wave in two different media.

Question 17

What is the defenition of internal reflection?

Answer 17

When a ray of light strikes the inner surface of a material and some of it reflects inside it.

Question 18

What is the defenition of critical angle?

Answer 18

The minimum angle of incidence at which total internal reflection occurs

Question 19

When does total internal reflection occur?

Answer 19

When the angle of incidence is greater than the critical angle.

Question 20

What is the critical angle of:
* water
* glass
* diamond

Answer 20

Water: 49
Glass: 42
Diamond: 25

Question 21

What makes the critical angle smaller/bigger?

Answer 21

The greater the refractive index of the material, the smaller the critical angle and vice versa.

Question 22

What is the equation for the refractive index?

Answer 22

n = sin i / sin r

Question 23

What is the equation for the critical angle?

Answer 23

n = 1 / sin c

Question 24

Draw a labled diagram of a converging lense with the rays.

Answer 24

Question 25

What are some of the uses of lenses?

Answer 25

• Spectacles
• Cameras
• Microscopes
• Telescopes

Question 26

How does a converging/concave lens look?

Answer 26

Question 27

How does a diverging/biconcave lens look?

Answer 27

Question 28

Principle focus

In a converging lens

Answer 28

Where the rays are concentrated together

Question 29

How does the focal length varry?

Answer 29

Depending on the thickness. The thicker the converging lens, the shorter the focal length.

Question 30

Enlarged

Answer 30

Used to desceibe an image that is bigger than the object.

Question 31

Diminished

Answer 31

Used to decribe an image which is smaller than the object.

Question 32

Inverted

Answer 32

Used to decribe an image which is upside down compared to the object.

Question 33

Principal axis

Answer 33

The line passing through the center of a lense perpendicular to its surface.

Question 34

Converging lens

Answer 34

A lens that causes rays of light parallel to the axsis to converge at the principal focus.

Question 35

Diverging lens

Answer 35

A lens that causes rays of light parallel to the axis to diverge from the principal focus.

Question 36

What are the features of the lenses in our eyes?

Answer 36

• They are flexible
• Muscles can change the shape and strength of the lens

Question 37

What does having flexible lenses in ours eyes help with?

Answer 37

It allows us to focus on objects at different distances.

Question 38

Why do some people need an extra lens for their eyes (contact lenses and glasses)?

Answer 38

Because some eyes are unable to change their strength enough to focus on either close or distant objects.

Question 39

Short sight

Answer 39

A person with short sight can see close objects clearly but not distant objects. The image forms in front of the retina.

Question 40

Long sight

Answer 40

Can focus on distant objects but not close ones. This is because the eyeball is too short and/or the lens cannot become strong enough so the rays from a close object cannot be converged enough to form a clear image on the retina.

Question 41

What is the order if the spectrom least refracted to most?

Answer 41

• Red
• Orange
• Yellow
• Green
• Blue
• Indigo
• Violet

Question 42

Spectrum

Answer 42

Waves, or colors of light, separated out in order according to their wavelengths.

Question 43

Dispersion

Answer 43

THe seperation of different wavelengths of light because they are refracted through different angles.