Explain the following:(i) In the active state of the transistor the e

1.	Explain the following:(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.
Answer» (i) Emitter base junction is forward biased whereas base collector junction is reverse biased. 1, (ii) Small change in the current Iu in the base circuit controls the larger current I. in the collector circuit. I_c = βIn (iii) Elemental semiconductor's band gap is such that the emitted wavelength lies in IR region. Hence cannot be used for making LED.

Explain the following:(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.

Answer»

(i) Emitter base junction is forward biased whereas base collector junction is reverse biased. 1,

(ii) Small change in the current Iu in the base circuit controls the larger current I. in the collector circuit. I_c = βIn

(iii) Elemental semiconductor's band gap is such that the emitted wavelength lies in IR region. Hence cannot be used for making LED.