P1 Revision (continued) - created from Mind Map

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 Enter text here

P1 Revision (continued)