Which of the following statements is not correct in the case of light emitting diodes (LEDs)? A. It is a heavily doped junction. B. It emits light only when it is forward biased. C. It emits light only when it is reverse biased. D. The energy of the light emitted is equal to or slightly less than the energy gap of the semiconductor used. Choose the correct answer from the options given below:
C and D
A
C
B
Correct answer:B
Standard Method
Given: Statements about light emitting diodes (LEDs) are listed, and we need the statement that is not correct.
Find: The correct option corresponding to the incorrect statement.
From the solution text:
Therefore, the incorrect statement is C. Among the given options, the option containing C alone is B.
Concept Check
Given: Basic properties of an LED.
Find: Which statement is false.
Use the standard LED facts:
So the statement saying it emits light only in reverse bias must be false. Hence the correct option is B.
Confusing the statement label with the option label. The incorrect statement is C, but the correct answer option is B because option B contains only C.
Assuming LEDs behave like ordinary diodes under reverse bias for light emission. LEDs emit light in forward bias, not reverse bias, because recombination responsible for photon emission occurs in forward bias.
Thinking photon energy must be exactly equal to the band gap in every case. In practice, the emitted light energy can be equal to or slightly less than the semiconductor band gap.
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