How do we represent light?

TG1: How do we represent light?

Hello.

Before we carry on,

make sure you have your 1B textbook and activity book with you.

Which of the two people will be able to see the flame?

Multiple Select

Which of the two characters will be able to see the flame?

• The boy looking through the straight tube

• The girl looking through the bent tube

The flame of a candle can be seen through the straight tube, but not through the bent hose.

We can sometimes see light coming through the gaps between leaves.

Light can also be seen emerging from spotlights in a light show.

Try page 1 of your activity book

Draw a representation of light, and explain why you drew it that way.

Poll

Have you finished your drawing?

• Yes, and I'm confident that I've done a good job

• Yes, but I'm not sure if it's okay

• No, I'll go do it now.

Based on what we've seen about light so far, we know 2 things:

• Light is emitted, or given out, from light sources. We see it when it reaches our eyes.

• Light travels in a straight line

Let's watch a video to see how our knowledge of light developed

There'll be a simple quiz after the video : )

Multiple Choice

What did Ibn Haytham's experiments prove about light?

• Our eyes give off light

• Light comes from sources outside of our bodies

• Ole Romer

Multiple Select

Which of these colours are contained in white light?

• red

• blue

• yellow

• green

Multiple Choice

Many scientists contributed to what we know about light today.

• True

• False

Let's learn some terms that scientists use to describe light.

A luminous object or light source is anything that produces or emits light.

Open Ended

Give an example of a light source/luminous object.

Some examples of light sources are:

• phones

• candles

• torchlights

• the sun (and other stars)

• light bulbs

A light ray is a thin line of light coming from a source.

A light ray can be represented by drawing

a line with an arrow.

The arrow shows the direction of the light ray.

Read the example on page 8 of your textbook

Try Q2 on page 3 of your activity book.

Open Ended

What was your answer to 2b? Why can John see bulb X?

Let's deepen our understanding.

A bundle of light rays is known as a beam

• Beams of light can be parallel, divergent or convergent.

What about shadows?

• An opaque object does not allow light to pass through it.

• When an opaque object blocks light, a shadow forms

• Shadows take the shape of the opaque object that is blocking the path of light.

  
  

Here's a ray diagram that explains how shadows form.

One last challenge:

Can you explain why the moon seems to change shape every night?

Watch the video, and draw ray diagrams in your Science journal to explain what's going on!