A LED produces light when

Electrical Engineering XYZ MCQs

A LED produces light when:

  1. Unbiased
  2. Forward biased
  3. Reverse biased
  4. None of the above

Correct answer: 2. Forward biased

Explanation: A Light Emitting Diode (LED) is a semiconductor device that emits light when current flows through it in the forward direction, meaning when it’s forward biased.

When a diode is forward biased, meaning a positive voltage is applied to the anode and a negative voltage is applied to the cathode, it allows current to flow through it. In the case of an LED, this forward current causes electrons to recombine with electron holes within the device, releasing energy in the form of photons. These photons are the light emitted by the LED.

When the LED is unbiased or reverse biased, it does not produce light. Unbiased means there’s no voltage applied across it, and reverse biased means the positive voltage is applied to the cathode and the negative voltage is applied to the anode, which prevents significant current flow through the LED.

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