P2: Radiation and Life Unit Summary

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

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

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

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!

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’.

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.

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

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