The Electromagnetic Spectrum

What is Light?

• Light is a form of radiant energy that you can see.

• The visible spectrum is only a small part of the range of radiant energies.

• The entire range of radiant energies is called the Electromagnetic Spectrum.

• Electromagnetic Spectrum:

• http://www.brainpop.com/science/energy/electromagneticspectrum/preview.weml

• Energy can be transmitted as a wave. Light travels as a wave.

Colours and Wavelengths

• We see different colours when the waves have different wavelengths.

• We measure wavelength in nanometers (nm) and the measurement is represented by the symbol lambda, λ.

The Wave

• One wavelength is the distance from crest to crest or from tough to trough.

Definitions…

• Amplitude: The crest height (or depth of the trough) from the equilibrium position.

How do Waves Travel?

• Waves transfer energy.

• The parts of the Electromagnetic spectrum have common properties, such as their high speed and ability to travel through a vacuum.

• Different properties are related to wavelength, frequency and energy.

Colours and their Wavelengths

• Red – 700 nm• Orange – 600 nm• Yellow – 580 nm• Green – 510 nm• Blue – 475 nm• Violet – 400 nm

Frequency

• Frequency: The number of cycles completed in a period of time.

• The unit of measurement is Hertz (Hz), which represents cycles/second.

• High frequency waves are shorter in wavelength and carry more energy.

Create your Own Electromagnetic Spectrum

• Using long blank white paper create a drawing of the electromagnetic spectrum.

• Include the types of waves (radiowaves, microwaves, etc), their range in wavelengths, the wavelengths, and a wave indicating frequency.