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LEDs that can emit red, yellow, orange, etc. commercially available.

1. How these colours are obtained in a LED.

2. Write any two uses of LED.

3. What are its advantages over ordinary bulbs?

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1. Different colours are obtained by changing the concentration of arsenic and phosphors in Gallium Arsenide Phosphide.

2. LEDs find extensive use in remote controls, burglar alarm systems, optical communication, etc.

3. LEDs have the following advantages over conventional incandescent low power lamps:

  • Low operational voltage and less power.
  • Fast action and no warm-up time required. 
  • The bandwidth of emitted light is 100A° to 500A° or in other words it is nearly (but not exactly) monochromatic.
  • Long life and ruggedness Fast on-o switching capability.

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