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Radiation and Life

(OCR)

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Light

White light is a mixture of colours:

RED LIGHT is made of “low energy

photons”

PURPLE LIGHT is made of “high energy photons”

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Intensity of light and heat

The light here is very intense!

The light here isn’t so bad... Why?

When a body absorbs radiation the amount of heat it gains

depends on the intensity and the time of the exposure.

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Ionisation Some types of radiation are dangerous because they “ionises” atoms – in other words, it turns them into ions by “knocking off” electrons:

Ionisation causes cells in living tissue to mutate, usually causing cancer. High doses can destroy cells completely, causing radiation sickness.

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Microwaves

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Protection against harmful radiation

A lead screen protecting from x-rays

Containment structures around a nuclear reactor

Sun cream to protect against ultra-violet radiation.

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Handling Radioactive Materials

Safety measures:

1) Keep your distance

2) Minimise exposure time

3) Protective clothing

4) Careful labelling

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The Greenhouse Effect We get heat from the sun:

A lot of this heat is _______ back into space.

However, most of it is kept inside the Earth by a layer of gases that prevent the heat escaping by _______ and then re-radiating it back again.

This is called the _________ Effect. It has always been around, but is currently being made worse due to:

1) Burning (releasing CO2)

2) __________ (removing trees that remove CO2)

3) Increased micro organism activity (from rotting ______)

4) Cattle and rice fields (they both produce _______)

These changes will cause GLOBAL WARMING and RISING SEA LEVELS

Words – methane, radiated, absorbing, deforestation, waste, greenhouse

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Ozone

Diagram showing the quantity of ozone in different parts of

the southern hemisphere

Global production of CFCs over the last 60 years

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The Carbon Cycle

CO2 in air

1. CO2 is taken in by plants for photosynthesis and turned into carbohydrates

2. Plants release CO2 through respiration

3. The carbon taken in by plants is then eaten by animals

5. Animals (and plants) die and their remains are fed on by microbes

6. These microbes also release CO2 through respiration

4. Animals release CO2 through respiration

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The Carbon Dioxide Balance Carbon dioxide levels in the atmosphere have remained balanced due to the carbon cycle. However, over the last 200 years the level of CO2 in the atmosphere has risen due to activities like:

1) Deforestation, which takes away some of the trees that remove carbon dioxide

2) Burning fossil fuels, which releases more carbon into the atmosphere that was previously “locked up”

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Global Warming

Facts:

1) The 10 warmest years of the last century have all occurred within the last 15 years

2) Sea level has risen by between 12 and 24cm in the last 100 years

3) Rainfall has risen by 1%

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