Ray model of light

Question 1

What is the speed of light

Answer 1

3.0times10 to the power of 8m/s

Question 2

When light falls on the object what will happen

Answer 2

Light can be reflected, refeacted or absorbed by the object(the more transparent, the less light absorbed)

Question 3

Rules of drawing ray diagram

Answer 3

1. Light rays are drawn as straight lines
2. real light rays are drawn as solid lines
3. virtual light rays are drawn as dotted lines
4. all real light rays must have arrows(virtuallight rays no need)

Question 4

what are the 2 laws of reflection

Answer 4

the angle of incidence is equal to the angle of reflection(angle measured beteween normal and ray)
The incident ray, the reflected ray and the normal all lie on the same place.

Question 5

For the different surfaces, what will light rays do?

Answer 5

For smooth surfaces, we can see clear reflected images,(regular reflection) and for rough surfaces, we do not see clear reflected images because all the light rays are scattered differently.(diffused reflection)

Question 6

what are real image and virtual image

Answer 6

real image: light fall where the image is so the image can be caught on the screen.
virtual image: Image can be seen but no light rays are passing through the location of the image so it is not caught on screen.

Question 7

• characteristics of plane mirrors

Answer 7

-upright
-same size as the object
-Image appears as far behind as the mirror as the object is in front of the mirror
-virtual
-laterally inverted(right become left)

Question 8

How to draw images formed by plane mirrors

Answer 8

1. draw a dotted line from the obejct (perpendicular to the mirror) and extend.
2. measure distance from ) to mirror
3. Mark I with the same distanc eat te other side
   4.Connect a line form I to the eye(bottom of eye if the image is given)(use dotted lines behind the mirror and solid line in fornt of the mirror.
   5.connect a line from the object to the point of incidence at the mirror.
   to check meadure angle of incidence and reflection

Question 9

Uses of plane mirror?

Answer 9

To check our apprearnace
make our homes or office to look wider
To reflect and change the direction light is going.

Question 10

What is a periscope

Answer 10

A periscope allows us to see what is behind a wall or around the corner without you being seen.

Question 11

What are the 2 types of curved mirrors and what is their purpose

Answer 11

Convex mirror and concave mirrors
A conves mirror produce virtual, upright and dimished images. It provides a wide field of vision and used when a large area needs to be seen.
A concave mirror produce virtual, upright and mgnified images. Used when a magnified image is needed. E.g. Used for makeuo and dentists. It can also be used in car’s healight to produce strong beams of reflected light.

Question 12

Can refraction occur for the objects that allow light to pass through?

Answer 12

Yes

Question 13

What is refraction

Answer 13

Refraction is the bending of light(changing direction of light) a sit passes from one transparent material to another due to the difference in the speed of light in the 2 different media.

Question 14

Rank the medias air, glass, water, vacuumm on which is optically denser.

Answer 14

Glass is denser than air
Water is denser than air
The least densest is vacuumm.

Question 15

What is “FAST”

Answer 15

If the medium denser–> slower –>bends towards noraml
If the medium less dense–>faster–>bend away from normal

Question 16

What is optical denstiy

Answer 16

It tells us how fast or slow light travels in that medium.

Question 17

Where does refraction take place

Answer 17

At the boundary

Question 18

When will there be no bending of light across diff medias

Answer 18

If the angle of incidence is 0 but the light will still slow down

Question 19

How to draw refraction phenomenon

Answer 19

1. draw the virtual image above the object
2. Draw 2 straight lines to the eye(on top and below the eye) in the water line to be dotted and above water line to be solid
   3.track back the light rays form object to water surface

Question 20

What is dispersion of light

Answer 20

It is the separation of white light into its spectrum of colours in this order red, orange, yellow, green, blue, indigo, violet

Question 21

?Dispersion can be achieved by what shape

Answer 21

prism

Question 22

How does dispersion happen

Answer 22

When white light enters, each colour component is refracted by a diff amount sio bends diff and slow down at diff entent.

Question 23

how do i combine the colours into white light again

Answer 23

using a second prism combining the colours.

Question 24

Light is the only type of ? that we can see and cannot see

Answer 24

Electromagnet(em) radiation
Infrared radiation
Ultraviolet(uv) radiation
Visible light

Question 25

Explain why object isnearer to the surface than it atcually is

Answer 25

When light rays form P come out of the water, they bend. However,our brain thinks that the light rays have moved in a straight line, so P appears to be at a higher position than it actually is.