1. ⇒ (MHT CET 2023 11th May Evening Shift )

In the study of transistor as an amplifier if $α = \frac{I_{C}}{I_{E}} = 0.98$ and $β = \frac{I_{C}}{I_{B}} = 49$ , where $I_{C}, I_{B}$ and $I_{E}$ are collector, base and emitter current respectively then $(\frac{1}{α} - \frac{1}{β})$ is equal to

A. zero

B. $\frac{1}{2}$

C. 2

D. 1

Correct Option is (D)

$\begin{aligned} \frac{1}{α} - \frac{1}{β} & = \frac{1}{0.98} - \frac{1}{4.9} \\ = 1.204 - 0.204 = 1 \end{aligned}$

2. ⇒ (MHT CET 2023 10th May Evening Shift )

Which one of the operations of $n - p - n$ transistor differs from that of $p - n - p$ transistor?

A. The emitter-base junction is reversed biased in $n - p - n$ transistor.

B. The emitter injects minority carriers into the base region of the $p - n - p$ transistor.

C. The emitter injects holes into the base of the $p - n - p$ transistor and electrons into the base region of $n - p - n$ transistor.

D. The emitter injects holes into the base of $n - p - n$ transistor.

Correct Option is (C)

Currently no explanation available

3. ⇒ (MHT CET 2023 9th May Evening Shift )

In a transistor, in common emitter configuration, the ratio of power gain to voltage gain is

A. $α$

B. $\frac{β}{α}$

C. $β α$

D. $β$

Correct Option is (D)

$\begin{aligned} Power gain = Voltage gain \times Current gain \\ ∴ \frac{Power Gain}{Voltage Gain} = Current gain = β \end{aligned}$

4. ⇒ (MHT CET 2021 21th September Morning Shift )

For a transitor, $\frac{1}{α_{DC}} - \frac{1}{β_{DC}}$ is equal to [ $α_{DC}$ and $β_{DC}$ are current amplification factors]

A. three

B. two

C. zero

D. one

Correct Option is (D)

$\begin{aligned} \frac{1}{α_{D C}} - \frac{1}{β_{D C}} = \frac{I_{e}}{I_{c}} - \frac{I_{e}}{I_{c}} \\ \frac{I_{e} - I_{b}}{I_{c}} = \frac{I_{c}}{I_{c}} = 1 \end{aligned}$

⇒Semiconductor Devices