Think back to last big teach...

Remember.. Last time we look at some of the properties of waves. Used terms such as wave length and frequency. Now we will apply our understanding. Topics in physics are often not stand alone, they link with other topics!

P1- Topic 2 Big Teach The Electromagnetic Spectrum

Specification Link

Specification Link

Herschel and Ritter... https://www.youtube.com/watch?time_continue=112&v=-JdhySH2PMc

Herschel Ritter Ideas behind experiment How was the temperature of the different parts of visible light different Experimenting with Silver Chloride for photography, Knew that it turned black when exposed to light. Equipment used Prism Thermometer Light Silver Chloride Observations Was hotter towards the red end of the spectrum and even hotter beyond the red Turned black faster towards violet and even faster beyond the violet Conclusions from observations Must be invisible light beyond the red part of visible light. Must be invisible light beyond the violet part of visible light. Name of type of wave discovered Infrared Ultraviolet

They have asked you to discuss two experiments, do one at a time! Things to remember… You can bullet point 6 mark questions, just make sure they are full sentences using correct scientific language They have asked you to discuss two experiments, do one at a time!

An explanation including some of the following points Results obtained: Herschel: temperature on thermometer Ritter: speed of darkening of silver chloride paper Trend of results: Herschel: hotter towards red end Ritter: quicker towards blue/violet end Extension of experiment to get more results: Herschel: measure below red; found it even hotter Ritter: measure above blue/violet; paper darkened quicker Conclusion: · Herschel: Must be radiation below red ( Infra Red) · Ritter: Must be radiation above blue/violet ( UV)  

ELECTROMAGNETIC SPECTRUM 740nm 370nm

The Electromagnetic Spectrum Key points you need to know... Electromagnetic waves that have long wavelengths have lower frequencies and less energy. And electromagnetic waves that have short wavelengths have high frequencies and high energy. LEARN THE ORDER!! Rich Men In Vegas Use eXpensive Gadgets (learn the order!) Think of your own pneumonic.

Electromagnetic Wave Uses Danger Radio Waves Telecommunications Radio None Microwaves Heating food Mobile phones Heat human body cells Possible link to brain tumours via mobile phone use. But no evidence Infrared Heating Night vision Remote controls Skin burns Visible Light To see Ultraviolet Rays Tanning Salons Detect forged bank notes Identify stolen goods Skin cancer (mutations) Cataracts X-Rays Detecting bones Airport security Ionising radiation- cell mutations that can cause cancer Gamma Rays Treating cancer Sterilising food

Not always so simple!

Key words… wavelength, frequency, energy

Ionising radiation?

Ionising Radiation... Gamma is Ionising- that means when it comes into contact with atoms it will make them lost electrons.

Why is this bad? We are made up of atoms. When atoms lose electrons they become ions. Ions are reactive. This causes the cells to mutate (because they are made up of atoms), which can lead to cancer!

Is Gamma the only type of ionising radiation?

https://www.youtube.com/watch?v=K_zc1WKT0CA

What you need to know... Ionising radiation is emitted by radioactive sources. Alpha, beta and gamma are all ionising. Alpha and beta are particles and gamma is a wave. Ionising radiation can knock of electrons in atoms which can lead to cell mutation and eventually cancer.

Want more questions? Past papers on singhscience and an exam booklet which is split up into the 6 different topics in P1.