Physics 1 Revision Lesson 5 Properties of waves and the Electromagnetic spectrum

General Properties of waves

Transverse waves Longitudinal waves coils vibrate source moves up and down direction of wave coils vibrate Longitudinal waves direction of wave

A peak is the tip of the wave, a trough is the bottom of a wave

The wavelength of any wave is the distance between two matching points on neighbouring waves.

Amplitude is the height of the wave, the greater the amplitude, the greater the energy

The frequency is the number of waves passing any point each second. frequency = number of waves past a point / time frequency is measured in hertz (Hz)

You can calculate the speed of a wave using the formula Speed = frequency (Hz) x Wavelength () A wave traveling in water has a frequency of 500 Hz and a wavelength of 3 m. What is the speed of the wave?

Electromagnetic Spectrum

higher frequency and energy The waves in the electromagnetic spectrum are transverse waves The have different wavelengths. And frequencies. The higher the frequency (and smaller the wavelength) the more energy the wave carries and the more dangerous it can be They travel at the same speed through a vacuum X-rays ultraviolet visible light infrared microwaves radio waves smaller wavelength higher frequency and energy

The electromagnetic waves can be used in communication Frequency Wave Uses Wavelength Lowest Radio waves Television and radio transmission Longest Microwaves Mobile phones Infra red Optical fibre communication Visible light Photography Ultraviolet Detecting forged banknotes and tanning X-rays Medical images of bones Highest Gamma rays Killing cancer cells Shortest

Reflection, Refraction and Dispersion

All waves will reflect off different surfaces. This means that instead of just passing into another medium, the waves bounce back. The angle of incidence is equal to the angle of reflection.

Refraction occurs when a wave travels through a different medium of a different density The wave changes direction and speed due to the higher density of the medium

Diffraction is when a set of straight (or 'plane') waves passes through a gap in a barrier. Curved waves come out the other side Diffraction produces a greater curved wave when the wave length is of a similar size to the gap

Key words and statements

Properties of waves and EM spectrum Transverse waves The number of waves per second Longitudinal waves A wave in which the particles move up and down at 90º to the direction of the wave movement Wavelength The height of the wave Amplitude The distance from one peak to the next peak or from one trough to the next trough Frequency The units for frequency Wave speed A wave in which the particles move backwards and forwards in the same direction as the wave movement Hertz A range of waves which all share the same properties but differ in wavelength and frequency Electromagnetic spectrum = frequency x wavelength

Properties of waves and EM spectrum Transverse waves The number of waves per second Longitudinal waves A wave in which the particles move up and down at 90º to the direction of the wave movement Wavelength The height of the wave Amplitude The distance from one peak to the next peak or from one trough to the next trough Frequency The units for frequency Wave speed A wave in which the particles move backwards and forwards in the same direction as the wave movement Hertz A range of waves which all share the same properties but differ in wavelength and frequency Electromagnetic spectrum = frequency x wavelength

Properties of waves and EM spectrum In the electromagnetic spectrum, as the frequency increases… Communication Electromagnetic waves can be used for… passes through a gap in a barrier. Curved waves come out the other side. The rule of reflection is… The light is now travelling through a denser substance and therefore it changes direction and slows down. This is called refraction Light bends as it goes through a block because… The amount of energy increases All electromagnetic waves are… Wavelength decreases Diffraction is when a set of straight (or 'plane') waves… The angle of incidence always equals the angle of reflection Diffraction produces a greater curved wave… Transverse waves As frequency increases… when the wave length is of a similar size to the gap

Properties of waves and EM spectrum In the electromagnetic spectrum, as the frequency increases… Communication Electromagnetic waves can be used for… passes through a gap in a barrier. Curved waves come out the other side. The rule of reflection is… The light is now travelling through a denser substance and therefore it changes direction and slows down. This is called refraction Light bends as it goes through a block because… The amount of energy increases All electromagnetic waves are… Wavelength decreases Diffraction is when a set of straight (or 'plane') waves… The angle of incidence always equals the angle of reflection Diffraction produces a greater curved wave… Transverse waves As frequency increases… when the wave length is of a similar size to the gap