Explain the construction details of LED

Explain the construction details of LED
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The construction of LED differs from normal standard diode in many aspects. As shown in the figure the p-n junction of the LED bulb is enclosed by a transparent, hard plastic epoxy resin hemispherical-shaped shell or body which protects the LED from shock and vibration.

LEDs have two terminals; a cathode and an anode. The cathode terminal is identified by either a flat spot on the body or notch or by one of the leads shorter than the other. The domed top of the LED is just like a lens concentrating the amount of light. The epoxy resin shell is constructed in such a way that the photons of light emitted by the junction are reflected away from the substrate base to which the diode is attached because LED junction does not emit that much light. Due to this, the brightest light will be emitted at the top of the LED.

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