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Description
Flashcards by Tabby Johnson , updated more than 1 year ago
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Created by Tabby Johnson
over 6 years ago
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| Question | Answer |
| What are the two types of waves and the key properties of each? | Longitudinal waves - the vibration of the particles is parallel to the direction of the wave travel, e.g sound waves & compression waves on a slinky toy Transverse waves - the vibration of the particles is perpendicular tot he direction of the wave travel, e.g EM waves, seismic waves and waves on a string/ wire. |
| What is polarisation? | Polarisation is when the vibrations of the waves are restricted wholly, or partially to a single plane |
| How is light polarised? | Passing unpolarised light through a polaroid filter which will only allow through light waves which are vibrating in a certain plane, therefore polarising the vibration of the light into one plane. |
| What is the difference between one complete cycle of a wave and the period of a wave? | The period of a wave is the time for one complete wave to pass a FIXED point. One complete cycle of a wave is the max. displacement to the next max. displacement ( e.g. one wave peak to the next ). |
| Define displacement, amplitude and wavelength. | DISPLACEMENT - ( of vibrating particles ) is known as its distance from its equilibrium position. AMPLITUDE - the max. displacement of a vibrating particle. ( from its equilibrium position ) WAVELENGTH - the least distance between two adjacent particles with the same displacement and velocity at the same time. |
| What is the equation to calculate the period of a wave, for waves of frequency, f? | |
| Equation to work out the wave speed | The higher the frequency of a wave the shorter its wavelength. So its wave speed will always be the same. |
| What is the phase difference of a vibrating particle and the equation to calculate phase difference? |
The phase is the fraction of a cycle a particle has completed in a certain time since the start. The phase difference between 2 particles vibrating at the same time and frequency is the fraction of a cycle between the vibrations of the two particles.
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Pdpd1 (binary/octet-stream)
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| What is equal to 1 radian | 1 cycle = 360 degrees = 2 radians |
| What are the 3 main properties of waves? | REFLECTION - when straight waves are directed at a certain angle to a hard flat surface and they reflect off at the same angle. REFRACTION - when wavefronts approach a boundary at an angle and they change direction and speed whilst passing through. DIFFRACTION - when waves spread out after passing through a gap or round an obstacle. |
| What two factors effect the way the waves spread out when diffracted ? | - The narrower the gap , the more the waves spread out - The longer the wavelength, the more the waves spread out |
| What is the dish design for, for satellites ? | The dishes are required to point south due to the way the satellites orbit the Earth. The bigger the dish the more radio waves it can reflect onto the aerial and therefor a stronger signal is received. However, the bigger dish diffracts the waves less so it needs to be aligned more carefully than a smaller dish to make sure the radio waves are focus is directly onto the aerial. |
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