Light

Light

How do we see non-luminous object?

What are the characteristics of an image formed by a plane mirror?

What are the effects and uses of reflecting surfaces?

Multiple Select

Which of these statements about light rays are true?

• Light travels in a straight line

• Light travels forward

• A bundle of light rays is called a beam of light

Recap

• Light travel in straight lines.

• Light rays are represented by a straight line with arrows indicating the direction of travel.

• Shadows are formed when light is blocked by an opaque object.

• Light travel in straight line from object into our eye, allowing us to see the object

How long would it take for us to realize if the sun went out?

How long would it take for us to realize if the sun went out?

• Light travels in the form of waves

• Speed of light: 300 000 000 m/s

• Distance from earth to sun: 150 000 000 000 m

• Time taken: 500 s

How do we see things?

• A luminous object gives out light and can also be called a light source.

• Light travels in a straight line directly into the eye.

Did you know...

• Some animals can produce their own light. This is called BIOLUMINESCENCE.

• It is normally produced by

  animals that live in dark

  environments such as caves,

  the deep sea or even just at

  night.

Multiple Select

An example of a luminous object is _______

• the moon

• the star

• the sun

• the sky

Open Ended

A white ball and a black ball are placed in a totally dark room. Which ball can you see?

A non-luminous object does not gives out light.

The bouncing of light rays off a surface is called reflection.

• Light from the light source strikes the book and bounced into your eye.

The moon is non-luminous

We are able to see it as it reflects light from the sun into our eyes.

Open Ended

A shiny ball (covered with mirrors) and a black ball are placed in a totally dark room. Which ball can you see?

We need a LIGHT SOURCE to see non-luminous object.

• We are able to see light sources as the light they emit enters our eyes.

• However, most object do not emit light (non-luminous).

• So how do we see non-luminous object?

  We need a LIGHT SOURCE to see non-luminous object.

• Light travel in straight line from object into our eye, allowing us to see the object

Multiple Choice

Figure 1 demonstrates light travels in

• zig zags

• circles

• a straight line

• random bursts

Multiple Choice

Figure 2 demonstrates

• Refraction

• Reflection

• Light travels in a straight line

• Rewind

Multiple Choice

The bouncing of light off an object is ....

• a mirror

• absorption

• reflection

• refraction

What do you notice about these images?

Have you seen this?

Take an artistic photo using a mirror and upload it onto this padlet link! 10 min for this task!

Multiple Choice

Which one of the following is the image obtained by the plane mirror ?

Multiple Choice

When the image of an object is seen in a plane mirror, the image is _____.

• real and upright.

• real and inverted.

• virtual and upright.

• virtual and inverted.

Multiple Choice

What is the distance of your image from you if you stand 1.5 m in front of a plane mirror?

• 1.5 m

• 2.0 m

• 3.0 m

• 4.5 m

Multiple Choice

A plane mirror always produce ________images.

• virtual

• real

• ideal

• refracted

Multiple Choice

If a 2.5 m object is placed in front of a plane mirror, the height of its image is

• less than 2.5 m

• 2.5 m

• more than 2.5 m

• 0