Light

Question 1

Where does the light come from?

Answer 1

luminous sources

Question 2

Give 5 sources of light.

Answer 2

sun, bulb, candle, fire, lightening

Question 3

What does the word luminous mean?

Answer 3

emits light

Question 4

How can we see objects which are not luminous?

Answer 4

The light rays hit the object and are reflected from it into our eyes

Question 5

What way does light travel and what is it called? Illustrate the different types.

Answer 5

Light travels in straight lines called rays.

Question 6

Name 2 types of prism/lens

Answer 6

concave prism/lens, convex prism/lens

Question 7

Draw how light passes through a concave prism and state what type of ray is created.

Answer 7

diverging

Question 8

Illustrate how light passes through a convex prism and state what type of ray it creates.

Answer 8

converging

Question 9

Give 5 pieces of evidence for light travelling in straight lines.

Answer 9

1. Shadows
2. The Pinhole Camera
3. Light streaming through water droplets in clouds
4. Light coming through the branches in a forest
5. Light in the laser beam.

Question 10

Decribe what a pinhole camera image is and draw a diagram to show how a pinhole camera works.

Answer 10

Image is INVERTED (upside down) and REAL (formed on a screen)

Question 11

In a pinhole camera:

1. Is the image on the screen inverted (upside down) or the right way up?
2. Is the image brighter or dimmer that the object?
3. Is the image smaller or larger than the object?
4. What is the effect on the image of moving the camera close to object?

Answer 11

1. inverted (upside down)
2. dimmer
3. smaller
4. gets bigger

Question 12

In a pinhole camera, if the pinhole is made larger, what happens to the (i) brightness and (ii) sharpness of the image?

Answer 12

(i) brighter, (ii) more blurred

Question 13

What is the name given to light travelling in straight lines?

Answer 13

RECTILINEAR PROPAGATION

Question 14

What is the lens in the eye like when looking at a near object

Answer 14

Looking at a near object the lens is fat

Question 15

What is the lens in the eye like when looking at a far object

Answer 15

Looking at a near object the lens in thin

Question 16

What happens to the height of an object as the distance of the pinhole camera is increased?

Answer 16

Height of an object is decreased as the distance of the pinhole camera is increased

Question 17

Light travels in straight lines at a speed of ___________.

Answer 17

300 000 000 m/s

Question 18

How are shadows created?

Answer 18

Shadows are cast when an opaque object stops light from reaching an area.

Question 19

Draw a diagram to show how a shadow of a circular object is created with a small light source, describe it.

Answer 19

Between A and B no light reaches the screen.

The shadow is sharp an completely dark.

This type of shadow is called an UMBRA.

Question 20

What happens if a extended (large) light source is used to create a shadow, illustrate and describe it.

Answer 20

There is an UMBRA and a PENUMBRA

There is an outer region on the screen where all the light can reach.
Between the outer region and the umbra is a ring-shaped region, a partial shadow called the PENUMBRA.
It is dim and not sharp.

Question 21

What is an eclipse of the (i) moon and (ii) sun called?

Answer 21

(i) lunar eclipse, (ii) solar eclipse

Question 22

Describe an eclipse of the moon

Answer 22

Question 23

Describe an eclipse of the sun

Answer 23