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I want to know why different colours appear when viewed with a different angle. Can anyone tell me why?

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At a fixed voltage, a particular single LED only emits one particular spectrum, see some examples… - You may want to be more specific about what you observe, it could have something to do with dispersion (like in rainbow), interference, absorption by a glass surrounding the diodes, reflection etc. etc. or you have some multi-colored diodes. – Luboš Motl Sep 23 '12 at 8:01
Do you mean an LED, or an LED/LCD display e.g. on a smartphone? LCD displays can change colour because they rely on the spacing of the liquid crystal molecules and this changes when viewed at an angle. – John Rennie Sep 23 '12 at 9:03

if it is only a LED light,i guess the different color display you cannot distinguish that,because it is very tiny. if you mean LED is a LED screen, that is because when the light pass through the surface,interference and reflection happened. if you mean LED display cannot see it from 2 edge of side,that is because total reflection,so now people begin to develop new LED display,there has a technology called "moth eyes".

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