NEET Physics Semiconductor Electronics Questions Solved

BOARD

Explain the following:

(3)

(i) In the active state of the transistor, the emitter base junction acts as a low resistance while base collector region acts as high resistance.

(ii) Output characteristics are controlled by the input characteristics in common emitter transistor amplifier.

(iii) LEDs are made of compound semiconductor and not by elemental semiconductors.

 

(i) Emitter base junction is forward biased whereas base collector junction is

reverse biased.

(1)

(ii) Small change in the current IB in the base circuit controls the larger current

IC in the collector circuit. IC = β IB

(1)

(iii) Elemental semiconductor’s band gap is such that the emitted wavelength

lies in IR region. Hence cannot be used for making LED

(1)

Difficulty Level:

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