Definitions

• Phase- the starting position of a 2nd coherent wave compared to another measured in degrees
• Periodic time- time taken in seconds for one complete cycle of a wave, vibration or oscillation
• Wavelength- the distance between two peaks
• Frequency- the number of waves produced in one second
• Amplitude: maximum displacement of a wave from its undisturbed position
• Oscillation: regular, repetitive motion
• Transverse wave: direction of oscillation is perpendicular to direction of wave
• Longitudinal wave: direction of oscillation is parallel to direction of wave
• Coherence: two or more sources of waves that have the same frequency and are in phase
• Diffraction: spreading out of waves behind an object
• Optical fibre- thin fibre of glass that relies upon total internal reflection so light rays can pass down the length of it
• Endescope: an optical device made of bundles of optical fibres
• Analogue signal: signal that continuously varies in both amplitude and frequency
• Digital signal: a signal made up of a stream of binary data in form of 0s and 1s
• Analogue to digital conversion- analogue signals are sampled continuously at fixed intevervals of time. Values are converted into binary so they can be sent as a digital signal
• Refraction: the change in direction of light when there is a change of speed as it crosses a boundary between a different media (e.g. air into glass)
• Total internal reflection: when light reflects within a medium instead of refracting across the boundary into another medium
• Critical angle: angle of incidence that causes an angle of refraction of 90°
• Total inner reflection occurs when angle of incidence = greater than critical angle
• Electromagnetic waves travel at same speed of light in a vaccum (3×10⁸ m/s)
• Superposition: when 2 or more waves combine their displacements are added together