The Electromagnetic Spectrum

Transverse Longitudinal BEFORE WE START... What are the two main classifications of waves? Transverse Longitudinal A wave transfers energy through a medium without the medium itself having to move. The energy is transferred by disturbances (oscillations) in the medium (material) through which the transfer is occurring. There are many different kinds of waves Electromagnetic waves pass through a vacuum & do not need to be carried by a substance. Light, infra red & microwaves all make things warm up. X-rays & gamma rays can cause ionisation and damage to cells, which also show that they carry energy. Loud sounds make things vibrate or move. Even the quietest sound move your eardrum Waves on the sea can toss big boats around and can generate electricity. Waves also transfer information, as well as energy. E.g. TV, radio, speech, fibre optics etc eg Light eg Sound Both involve vibrations Both transport energy Neither transport matter 2

USING A PRISM TO PRODUCE A SPECTRUM OF COLOURS Draw a diagram Try to explain why a spectrum of colours is produced from ‘white light’   RED ORANGE YELLOW GREEN BLUE INDIGO VIOLET THE COLOURS ARE PRODUCED BY ‘DISPERSION’ WHITE LIGHT IS MADE UP FROM THE COLOURS OF THE SPECTRUM

Electromagnetic Spectrum There are seven types of electromagnetic wave which form the electromagnetic spectrum (EMS). The spectrum extends from long wavelength, low frequency radio waves to short wavelength, high frequency gamma rays. Wavelength

Solar Radiation The Sun produces solar radiation which contains different forms of electromagnetic radiation, e.g. visible light, ultraviolet, infra red.

Electromagnetic Spectrum For all forms of electromagnetic radiation, there are four key terms to understand: Amplitude The distance of the peak above the centre line or the distance of the trough below the centre line.

Electromagnetic Spectrum For all forms of electromagnetic radiation, there are four key terms to understand: Wavelength The distance from peak to peak or trough to trough.

Electromagnetic Spectrum For all forms of electromagnetic radiation, there are four key terms to understand: Frequency The number of complete waves per second, measured in Hertz (Hz). This wave has a frequency of about 2Hz, as two complete wavelengths pass each second.

Electromagnetic Spectrum For all forms of electromagnetic radiation, there are four key terms to understand: Wave Speed The distance the wave travels per second. All electromagnetic waves travel at 3 x 108 m/s in a vacuum.

Waves - Key Terms

Properties of Electromagnetic Waves All electromagnetic waves: Are transverse waves. Transfer energy from one place to another. Can travel through a vacuum. Travel at the same speed. The speed of light in a vacuum is 300,000,000m/s. Consist of oscillating electric and magnetic fields. Can be reflected, refracted or diffracted.

How Many Applications of EMS Do You Know? Drag the application to the correct box...