P1 Revision (continued) - created from Mind Map

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A spectrum of waves

Transverse waves- travels in a direction at right angles to the water vibration

Amplitude- the maximum displacement of a particle from its rest position

Wavelength(m)- distance between two successive points on the wave

Frequency(Hz)- number of complete waves passing a point in one second

Crest- point of maximum displacement above the rest position

Trough- maximum displacement below the rest position

wave speed(m/s)= frequency x wavelength

Electromagnetic spectrum

Radio waves- lowest frequency

All electromagnetic waves travel in straight lines through a particular medium

They can be reflected and refracted

(REFLECTION) When a ray of light hits a mirror the angle of incidence is equal to the angle of reflection

(REFRACTION)When light passes from one medium into another at an angle to the boundary, it changes direction. This sometimes produces off effects at the boundary between two mediums

Some are used for communication

When a wave travels from one medium into another, the frequency of the incident wave does not change. The wavelength does because the speed of the wave changes. Electromagnetic waves slow down in a denser medium

When they are incident at an angle to the boundary, this change in speed causes the wave direction to change. This is known as refraction

In communications the size of the receiver depends on the wavelength of the wave. The longer the wavelength, the longer the receiver needs to be

When waves pass through an opening they spread out. This is known as diffraction

Light and lasers

Light Amplification by Stimulated Emission of Radiation

A laser produces a narrow intense beam of light of a single colour (monochromatic)

Uses of lasers- Communication, dental treatment, weapon guidance, surgery, light shows and bar code readers

Morse code- series of dots and dashes that represent individual letters in the alphabet. This is a digital signal. To cover large distances, the signals are relayed from one signal station to another

Signals can be sent by light, electricity, radio waves or microwaves

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