chapter 12 _international science_student's copy

7/29/2019 Chapter 12 _International Science_student's Copy

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Click to edit Master subtitle styleChapter 12Chapter 12

LIGHT

By: Ms Sumathi


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A source of light makes light. The _________ andother stars, fires, torches and lamps all maketheir own light and so are examples of sourcesof light.

Some animals, such as _________ and _________,are light sources. They make their own light toattract ________.

A _______ is not a source of light. It doesn't make

its own light, it just reflects light.The ________ is not a source of light. It reflects

light from the Sun. Objects which produce light are called

__________objects

Sources of lightSources of light


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What happens when LIGHT hits an object?

Three (3) things can happen. Light passes through easily (if the object is

__________) Light is blurred (if the object is

____________) Light is blocked (if the object is __________)

Opaque, transparent andOpaque, transparent and

translucent materialstranslucent materials


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Transparent materials let light pass through them in straight lines, so thatyou can see clearly through them. _________ is an example of atransparent material.

Translucent materials let some light through, but they scatter the light inall directions, so that you cannot see clearly through them.

________________ is an example of a translucent material.

Opaque materials do not let any light pass through them. They block thelight. _________ is an example of an opaque material.

.


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A shadow is made when an object blocks light. The shadowappears on the side of the object furthest from the _______source.

The object must be __________ or ___________ to make a shadow. Atransparent object will not make any shadow, as light will passstraight through it.

Opaque objects make _________ shadows. Translucent objectsmake faint shadows.

If an object is moved closer to the light source, the shadow gets____________.

If an object is moved further away from the light source, the

shadow gets ____________.

Light and shadowsLight and shadows


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The Sun is a very bright natural light source. It seems to

move across the sky during the day. In fact it just lookslike it does that because the Earth is spinning. The Sun casts (makes) the __________ shadows at the

_________ and ______ of the day, when the Sun is _______in the sky.

The Sun casts the _________ shadows at midday, when theSun is __________ in the sky.

Early morning-the Sun is low in Mid day- the Sun is highin

sky and casts a long shadow sky and cast shortshadows

Shadows made by the SunShadows made by the Sun


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The visible spectrum White light can be split up using a

_______ to form a spectrum. Aprism is a block of glass with a

triangular cross-section. Thelight waves are refracted asthey enter and leave the prism.

The shorter the wavelength ofthe light, the more it isrefracted. As a result, red light isrefracted the ________ and violetlight is refracted the ________,causing the coloured light tospread out to form a spectrum.

What is a spectrum?What is a spectrum?


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Refraction from a prismRefraction from a prism


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How a rainbow isHow a rainbow is

formed?formed?


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The Steps Involved inThe Steps Involved in

Rainbow FormationRainbow Formation1. Light from Sun strikes raindrop

2. Some of the light is reflected

3. The rest of the light is refracted

4. Light splits into component colours5. Reflected at rear of raindrop (TIR)

6. Refracted again as it leaves raindrop

7. Colours are further dispersed


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The birth of each rainbow begins with millions of tiny raindroplets which serves as a type of __________ of light. White light enters one individual rain droplet and exits as one

specific colour of the spectrum. If you only had a few raindroplets you would only see a few colours. This is typicallywhy rainbow appear after a rain storm.

Each rain droplet has a function in the formation of therainbow. Sunlight enters the rain droplet at a specific angleand the rain droplet separates the white light into manydifferent colours.

What color is refracted depends upon the critical angle,which is the angle the sunlight strikes the back of the raindroplet.

Red light bends the _________, exiting the rain droplet at a______degree angle, while__________bends the _________,exiting the rain droplet at a______degree angle.

All of the other colours of the rainbow exit the rain droplets atsome angle between 40 and 42 degrees, thus making upthe colours of the rainbow ROYGBIV, this order never

changes.

How a Rainbow is FormedHow a Rainbow is Formed

chapter 12 _international science_student's copy

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