Term
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Definition
| A wave transports energy from one place to another |
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Term
| What are mechanical waves? |
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Definition
| Mechanical waves use particles to transfer energy (neighbouring particles bump into each other and set their neighbours moving). Eg. sound waves use air particles so it cannot travel through a vacuum (a vacuum is empty space with no particles in it at all!). Sound travels faster through solids than liquids than gases because the particles are more closely packed. |
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Term
| What are electromagnetic waves? |
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Definition
| Electromagnetic waves don't use particle vibration to transfer their energy (in fact particles interrupt their progress through a material) and can therefore travel through a vacuum. e.g. light |
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Term
| What is the unit of frequency? |
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Definition
| Frequency is measured in hertz (Hz) |
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Term
| What is the wave equation? |
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Definition
| wavespeed = frequency x wavelength |
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Term
| Define a longitudinal wave. |
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Definition
| The vibrations in a longitudinal wave are parallel to the direction in which the energy is travelling. Eg. sound. [image] |
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Term
| Define a transverse wave. |
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Definition
| The vibrations in a transverse wave are perpendicular (at right angles) to the direction in which the energy is travelling. Eg. light. [image] |
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Term
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Definition
| Wavelength (lamda a Greek letter 'l') is the shortest distance between two particles that are oscillating in phase. (Distance between two crests on a displacement/distance graph). It is measured in metres (m)
[image] |
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Term
| What is the period of a wave? |
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Definition
| Period (T) is the time taken for one complete oscillation of a particle in the wave. (Distance between two crests on a displacement/time graph). It is measured in seconds (s). [image] |
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Term
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Definition
| Amplitude (A) is the maximum displacement from the mean position. (To the top of a crest or bottom of a trough from the middle line in either graph). [image] |
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Term
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Definition
| Frequency (f) is the number of oscillations per second. It cannot be read directly off a graph. You need to find (T) from the displacement/time graph and then find its reciprocal (f =1/T) |
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Term
| What are analogue signals? |
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Definition
| Analogue signals contain all the information as a continuously varying wave. [image] |
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Term
| What are digital signals? |
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Definition
| Digital signals are a series of pulses - either high or low - on or off - sometimes expressed as binary code 1s and 0s. [image] |
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