LS2 Science- Light

Question 1

P.S: The notes for drawing diagrams are not included, pls refer to notes instead for dat

Answer 1

Wouldst thou tellest me, how thou shalt draw with keyboard

Question 2

Light rays

Answer 2

A thin line coming from a source

It can be:

• Parallel
• Divergent (Spreading out)
• Convergent (Focusing to a point)

Question 3

Rays and Beams

Answer 3

Ray: A thin line of light
Beam: A stream of light rays

Question 4

Shadows (How are they formed?)

Answer 4

A shadow forms when light is
- blocked by an opaque object
- does not pass through the opaque object
(A shadow takes the shape of the object blocking the path of light)

Question 5

Define ‘Reflection’ (15.2)

Answer 5

The bouncing of light rays off a surface is called reflection

Question 6

PROPERTIES of ‘Reflection’

Answer 6

• Distance of object from mirror = Distance of image from the mirror 
• The reflection is 
- Upright
- Virtual
- Laterally inverted [Mirror image]
- Of equal size of the object

Question 7

LAWS of reflection

Answer 7

1. The incidence ray, reflected ray and the normal at the point of incidence lie on the same plane
2. ∡ of reflection = ∡ of incidence

Question 8

Regular reflection

Answer 8

• Occurs on a smooth surface
• Image: Clear and undistorted
• Light remains parallel after reflection

Question 9

Irregular reflection

Answer 9

• Occurs on a rough/ irregular surface
• No image is formed at the surface
• Light scatters in different directions after reflection

Question 10

Plane mirrors

Answer 10

Form undistorted and upright images. (Parallel)

• FLAT surface
• Can change the direction of light by reflection
• Upright image
• Laterally inverted
• Virtual image
• Distance from image→mirror = Distance from object→mirror

Question 11

Concave mirrors

Answer 11

Form magnified images. (Convergent)

• Have a surface that bends INWARDS
• Reflects light into a single point (Converging mirrors)
• Can reflect light rays from a point source into a parallel light beam
• If the object is further away: Forms an inverted image
  Example: Flashlights have a concave mirror inside to reflect a strong beam of light (2nd last page of notes)

Question 12

Convex mirrors

Answer 12

Form upright, distorted and smaller (than the object) images. (Divergent)

• Have a surface that bends OUTWARDS
• Cover a wider field of vision: Allows many things to be seen (E.g. surveillance)