Physics CP4+5

Waves transfer…

Energy and information but not matter

Frequency

The number of complete cycles of the wave passing a point each second

Period

Amount of time it takes for one full cycle of a wave

Amplitude

Maximum displacement of a point on a wave from its rest position

Wavelength

Length of a full cycle of the wave

Period equation

1/frequency

In transverse waves…

Oscillations are perpendicular to the direction of wave travel

Transverse waves examples

Ripples in water, EM waves and seismic s-waves

In longitudinal waves…

Oscillations are parallel to the direction of wave travel

Types of longitudinal waves

Sound waves, seismic p waves

Wave speed equation one:

Speed= frequency x wavelength

Wave speed equation 2:

Speed= distance/time

When waves hit a boundary, they are…

Absorbed, transmitted or reflected

Absorbed

Energy is transferred to the materials energy stores

Transmitted

The wave continues travelling through the material leading to refraction

Reflected

The wave is bounced off the material

angle of incidence

the angle between the incident ray and the normal

angle of refraction

the angle between the refracted ray and the normal

angle of incidence=

angle of refraction

If the wave speeds up, the…

wavelength increases and it bends away from the normal

If the wave slows down…

The wavelength decreases and it bends towards the normal

Shorter wavelengths…

Bend more

Order of EM spectrum

Radio, micro, infrared, visible light, ultraviolet, x-rays and gamma rays

As you go along the line of the EM spectrum…

Frequency increases, wavelength decreases

Radio waves are used for

Broadcastings and communications

Microwaves are used for

Microwaves and communications

Visible light is used for

Photography and illumination

Infrared radiation is used for

Thermal imaging and TV remote controls

UV waves are used for

Sterilising water and detecting forged bank notes

X rays are used for

Looking inside objects and airport security scanners

Gamma rays are used for

Detecting and treating cancer, sterilising food

Danger of microwaves

Heats up cells in our body

Danger of infrared waves

Causes skin burns

Danger of ultraviolet waves

Damages eyes, causes skin cancer

Danger of x rays and gamma waves

Cause mutations which can lead to cancer

Why does light split into different colours when shined through a prism?

Different wavelengths travel at different speeds so refract by different amounts