1. P2: Radiation and Life
Unit Summary

2. Taking Chances with the Sun
Sunlight provides energy for the Earth, can alter our mood, and allows our body to produce Vitamin D
Sunlight contains UV radiation which can cause burns and cancer
Melanin pigment in your skin prevents damage
Lots of melanin

3. Sunlight and Life
When an object absorbs EM radiation, it receives energy (ex-microwave radiation absorbed to heat food).
Ozone layer (O3) is good at absorbing UV rays, but allows visible light and radio waves through
CFC’s create holes in the ozone layer.
Plants use light energy
to power photosynthesis

4. Selecting Colours
We see objects because light travels in straight lines and bounces off objects into our eyes.
Luminous objects transmit light directly into our eyes.
Objects appear different colours because of absorption.
Blue arrow absorbs all
colours except blue

5. Microwaves
Microwave radiation transfers energy to absorbing substances (water, sugar, fat)
These materials vibrate and get hot.
Microwaves are efficient because most energy goes to heating food.
The centre of food
is usually the hottest!

6. Mobile Phones
Mobiles receive microwave radiation from nearby phone masts and send microwaves back.
Patterns in the radiation carry info.
The bones in your skull absorb some radiation (and your brain heats slightly!)
The intensity of the
microwaves decreases
with distance from the
mast.
Mobile use could cause cancer.
Use the Precautionary Principle…
‘better safe than sorry’.

7. X-Rays X-rays are very penetrating and an ionizing form of EM.
They work because they pass through soft tissue like skin and muscle and are absorbed by bone.
There is a correlation (link) between X-rays and cancer.
We also know the mechanism by which cancer is caused.

8. because of the contents in
The Greenhouse Effect
The GE is a natural phenomenon. Without it, the Earth would be too cold to live on.
BUT…because of Co2 emission, we have accelerated the heating of the Earth and this is called Global Warming.
We know the Earth is
heating at a rapid rate
because of the contents in
POLAR ICE CAPS

9. The Carbon Cycle Carbon is present in the atmosphere as CO2.
Humans are contributing to high levels of CO2.
Volcanoes are
also sources
of CO2
Dead matter
Decomposing
Releases CO2