optics quiz #1

Question 1

what is light?

Answer 1

• Light is energy transmitted through radiation.
• it can travel through empty space - it does not require a “medium”

Question 2

what do we know about light?

Answer 2

• the sun emits light in all directions through the vacuum of outer space
• earth captures only a tiny fraction of the sun’s light

Question 3

how fast and how does light travel?

Answer 3

• it travels fast; a billion km/h
• it travels in straight lines

Question 4

how many sources of light are there and what are they?

Answer 4

2
luminous sources and non-luminous sources

Question 5

what is it called when things give off light because they get hot?

Answer 5

incandescent

Question 6

what is luminescence?

Answer 6

when light is given off by things that do not get hot.

Question 7

how many types of luminescence lights are there?

Answer 7

5

Question 8

a glow stick is an example of which type of light?

Answer 8

chemiluminescence

Question 9

what does bioluminescence mean?

Answer 9

light that is released during chemical reactions in living things

Question 10

crushing crystals makes what kind of light?

Answer 10

triboluminescence

Question 11

glow in the dark objects is what type of light?

Answer 11

phosphorescence

Question 12

laser light

Answer 12

• Produces electromagnetic waves of exactly the same energy level
• Very intense
• Concentrated in one narrow beam

Question 13

Electric discharge

Answer 13

When an electrical current being passed through a gas results in light emission

Question 14

Geometric optics

Answer 14

the use of light rays to determine how light behaves when it strikes an object.

Question 15

transparent

Answer 15

transmits all or almost all incident light
objects can be clearly seen through the material

Question 16

translucent

Answer 16

transmits some incident light, but absorbs or reflects the rest
objects cannot be seen through the material

Question 17

opaque

Answer 17

does not transmit any incident light
all incident light is either absorbed or reflected
objects behind the material cannot be seen at all

Question 18

light ray

Answer 18

a line on a diagram representing the direction and path that light is travelling

Question 19

mirror

Answer 19

any polished surface reflecting an image and path that light is travelling

Question 20

incident light

Answer 20

light emitted from a source that strikes an object

Question 21

image

Answer 21

reproduction of an object through the use of light

Question 22

reflection

Answer 22

the bouncing back of light from a surface

Question 23

The ray model of light is?

Answer 23

A ray of light bounces off a plane mirror, this is also defined as reflection.

Question 24

Characteristics of images are?

Answer 24

Size - larger, the same, or smaller
Attitude - inverted or upright
Location - distance away from mirror
Type - real or virtual

Question 25

Curved/ Convex mirrors

Answer 25

- concave mirrors are also called converging mirrors because parallel light rays converge - convex mirrors are also called diverging mirrors because parallel light rays diverge

Question 26

what is a virtual image?

Answer 26

A virtual image is an image formed by rays that appear to be coming from a certain location (i.e. behind the mirror), but actually are not. These images cannot be seen on a screen.

Question 27

what is a real image?

Answer 27

A real image is an image formed by rays that converge (meet) at a certain location. These images can be seen on a screen.

Question 28

what is the centre of curvature?

Answer 28

centre of sphere

Question 29

what is the vertex?

Answer 29

point where principal axis meets mirror

Question 30

what is the point of focus?

Answer 30

the point thru which light rays parallel to the principle axes converge when they are reflected from a curved mirror

Question 31

what is the principal axis?

Answer 31

line through C & V to midpoint of mirror; normal to the surface of the mirror

Question 32

How can the rays help us find the image formed by a concave mirror?

Answer 32

1. Draw a ray coming in parallel to the PA and draw its reflection. 2. Draw a ray coming in through the focus and draw its reflection. 3. Draw a ray coming in through the centre and draw its reflection. 4. Where the three reflected rays converge, the image is there!