Optics 5: Making Rainbows

• Physics
• Secondary Education
• Age 13

Forces and Motion

Lesson 12. 

Dispersion of Light

How are you today?

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Highlights of the Day

• explain that white light is made of many colours and this can be shown through the dispersion of white light using a prism.

• Values :  Responsibility and Determination

Intro Questions

Class Discussion

• Do you ever see a rainbow at night?
• Does the Sun have to be shining to enable you to see a rainbow?
• Does there have to be rain or recent rain to enable you to see a rainbow?
• What colours can you see in a rainbow?

Do you ever see a rainbow at night?

YES

NO

Does the Sun have to be shining to enable you to see a rainbow?

YES

NO

Does there have to be rain or recent rain to enable you to see a rainbow?

YES

NO

What colours can you see in a rainbow?

Challenge Questions

Who was the scientist shown earlier?

1. Isaac Newton
2. Albert Einstein
3. Nikola Tesla
4. Bill Gates

In the year _____________ , Newton showed that white light could be split into different colours.

1. 1666
2. 1777
3. 1888
4. 1555

• Newton used light from the Sun, coming through a hole. 

• Newton used a glass block in the shape of a triangle to split the light into its colours. 

• He shone the colours onto a screen.

From which source of light did Newton use in his experiment?

1. Moon
2. Sun
3. light bulb
4. lamp

What shape of glass block was used by Newton in his experiment?

1. spherical
2. rectangular
3. triangular
4. cylindrical

• The range of colours that can be seen in white light is called a spectrum. 

• In the spectrum, the colours are not separate but they merge from one to another.

What is the name given to the range of colors that can be seen in white light?

1. rainbow
2. spectrum
3. light ray
4. incident ray

In the spectrum, what does the colours of light do to make visible white light back?

1. combine
2. separate
3. reflect
4. refract

What acronym will you use to remember the 7 colours of the visible white light spectrum?

Forces and Motion

Lesson 12. 

Dispersion of Light

Triangular prism

A ______________ is a solid shape such as the one that Newton used.

1. mirror
2. prism
3. metal
4. surface

• Dispersion means splitting light into different colours.

• Dispersion happens because light is refracted.

• Each of the different colours of light that make up white light is refracted through a slightly different angle. 

Self-survey: Rate your level of understanding and participation in this lesson.

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