Q25 / 237 · NTA Abhyas (NEET) 2020 · Physics · Semiconductors

In NPN transistor 1010 electrons enters in emitter region in 10-6 s . If 2% electrons are lost in base region then collector current and current amplification factor β respectively are

  • Correct answer
    A
    1.57 mA, 49
  • B
    1.92 mA, 70
  • C
    2 mA, 25
  • D
    2.25mA, 100

Solution

For given electrons

Emitter current Ie=neet

Where ne is the number of electrons enters into the emitter, e is the charge on electron and t is time.

Ie=1010×1.6×10-1910-6

Ie=1.6×10-3

Ie=1.6 mA

2% electrons are lost in base region hence base current Ib=2%×1.6×10-3 , therefore Ib=0.032 mA

Therefore Ic=Ie-Ib

Ic=1.6-0.032

Ic=1.57 mA

and the current amplification factor

β=IcIb=1.5680.032=49

Hence, the correct answer is option: 'A'.

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