C/W 2 nd November 2011 Microwaves Keywords: absorb microwave sample bias Objectives: Must – Understand the heating effects of radiation can damage cells.

C/W 2nd November 2011

Microwaves Keywords: absorb microwave sample bias

Objectives:Must – Understand the heating effects of radiation can damage cellsShould – Know what microwaves can be used for. Could – Understand how risks can be assessed.

Starter Why do microwave ovens cook potatoes but our phones don’t cook our heads? Write down 3 reasons in the back of your book.•Microwave ovens are more intense•Microwave ovens are on for longer•Microwave ovens use a grater (or higher) frequency (so more energy)

HHo

What type of electromagnetic wave would a paper clip in a plug produce?In P3 we will learn that mains electricity has a frequency of 50Hz

So 50 Hz radio waves.

C/W 3rd November 2011

Ozone Keywords: ozone

Objectives:Must – Understand that ozone protects living organisms Should – Know whether to accept different risks

Electromagnetic Spectrum

Radio

Micro

Infra-Red

Light

Ultra-V

iolet

X rays

Gam

ma

Wavelength () increases

Can you think of a phrase that would help you remember this order? Gate X Usually Lets In Most Radiation

High frequency

Short wavelength

High energy

Most penetrating

High frequency

Short wavelength

High energy

Most penetrating

Low frequency

Long wavelength

Low energy

Least penetrating

Low frequency

Long wavelength

Low energy

Least penetratingx

UV radiation Produced by the sun the 3rd highest energy after X-rays and gamma rays. So can be dangerous.

We can also get UV lamps......

UV can be dangerous does anything protect us?

Thomas Midgley, Jr.

Despite good intensions this chemist had a complete mare!

1st he introduced leaded petrol....

Then using CFC’s in fridges......

These two developments had very serious negative effects on the environment.

Ozone protects us from some of the Suns UV rays., by absorbing them

Ozone sheet

This picture shows the hole in the ozone layer

Why is this hole a problem?

Write down 2 reasons in your book.

1) Ice caps melt2) More chance of skin cancer

•Higher level !•How is ozone made? •Ozone is made when high energy UV radiation from the sun are absorbed by oxygen molecules and they react together making O3

• Ozone can react with other molecules like nitrogen, hydrogen, bromine and chlorine compounds. Which changes this part of the atmosphere.

Subheading - How can we protect ourselves from UV radiation?

-sun cream -Cloths

-Complete book problems page 246

H

Plenary

Tell your partner one thing you have learnt today, then swap, then tell somebody else. I will ask you what they have learnt!

Boswells physics blog

http://boswellsphysics.blogspot.com/

http://www.youtube.com/watch?v=Ws6AAhTw7RA

C/W 3rd November 2011

Ozone Keywords: ozone

Objectives:Must – Understand that ozone protects living organisms Should – Know whether to accept different risks