Semi conductor devices practice · Mixed difficulty

In BJT, maximum current flows in which of the following?

Three amplifier stages each with a gain of 10 are cascaded. The overall gain is

The coordination number of $Cu$ is

The logic behind ‘NOR’ gate is that it gives

Which of the following is not equal to 1 in Boolean algebra?

The band gap in germanium and silicon in $eV$ respectively is

A semiconducting material has a band gap of $1 \mathrm{~eV}$. Acceptor impurities are doped into it which create acceptor levels $1 \mathrm{~meV}$ above the valence band. Assume that the transition from one energy level to the other is almost forbidden if $k T$ is less than $1 / 50$ of the energy gap. Also, if $k T$ is more than twice the gap, the upper levels have maximum population. The temperature of the semiconductor is increased from $0 \mathrm{~K}$. The concentration of the holes increases with temperature and after a certain temperature it becomes approximately constant. As the temperature is further increased, the hole concentration again starts increasing at a certain temperature. Find the order of the temperature range in which the hole concentration remains approximately constant.

Statement I: NOT gate is also called invertor.

Statement II: NOT gate inverts the input signal.

A n – p – n transistor having a.c. current gain of 50 is to be used to make an amplifier of power gain of 300. What will be the voltage gain of the amplifier

The maximum efficiency of full wave rectifier is

A $P$-type semiconductor can be obtained by adding

The electrical resistance of depletion layer is large because

In a properly biased transistor

The conductivity of a semiconductor increases with increase in temperature because

In a reverse biased diode when the applied voltage changes by 1 V, the current is found to change by $0.5\,\mu A.$ The reverse bias resistance of the diode is [in ohm]

Assertion: Photodiode work in reverse bias.
Reason: Change in diode current increases with increase in intensity.

Calculate the number of states per cubic metre of sodium in $3 \mathrm{~s}$ band. The density of sodium is $1013 \mathrm{~kgm}^{-3}$. How many of them are empty?

Why is there sudden increase in current in zener diode?

In Boolean algebra, $\overline {\bar A \cdot \bar B}$ is equal to

A common emitter amplifier gives an output of 3V for an input of 0.01 V. If $\beta$ of the transistor is 100 and the input resistance is $1\,k\Omega ,$ then the collector resistance is

The Boolean expression ${P}+\overline{{P}} {Q}$, where ${P}$ and ${Q}$ are the inputs of the logic circuit, represents

Which one of the following statements is not correct

The value of ripple factor for full wave rectifier is

Respective ripple factor and efficiency of a full wave Rectifier are:

The truth table shown in figure is for
A    0   0   1   1
B    0   1   0   1
Y    1   0   0   1 

Statement I: A Zener diode is used to get constant voltage at variable current under reverse bias.

Statement II: The most popular use of Zener diode is as voltage regulator.

Which of the following is correct, about doping in a transistor?

Statement-I: For a given applied voltage, conduction current in n-type semiconductor is more than that in p-type semiconductor.

Statement-II: Mobility of electrons is greater than that of holes.

In half wave rectification, if the input frequency is
120 Hz, then the output frequency would be:

When $A$ is the internal stage gain of an amplifier and $\mathrm{\beta }$ is the feedback ratio, then the amplifier becomes as oscillator if