AIIMS Physics Semiconductor Electronics Materialsdevices Simple Circuits Class 12 Questions

Assertion: Photodiode and solar cell work on same mechanism. Reason: Area is large for solar cell.

Photodiode is a reverse biased p-n junction that consumes light energy to generate electric current. The change in the diode current depends on the number of photons it received. The number of photons are more if the intensity of light is more. Hence, both assertion and reason are true but reason is not the correct explanation of assertion.

What is the voltage gain in a common emitter amplifier, where input resistance is 3Ω and load resistance 24Ω, β = 0.6?

When an impurity is doped into an intrinsic semiconductor, the conductivity of the semiconductor

A pure semiconductor has equal electron and hole concentration of 10¹⁶ m⁻³. Doping by gallium increases nₕ to 5×10²² m⁻³. Then, the value of nₑ in the doped semiconductor is

Assertion: An N-type semiconductor has a large number of electrons but still it is electrically neutral. Reason: An N-type semiconductor is obtained by doping an intrinsic semiconductor with a pentavalent impurity.

Assertion: Electron has higher mobility than hole in a semiconductor. Reason: Mass of electron is less than the mass of hole.

A transistor is a current operating device because the action of transistor is controlled by the charge carriers. Base current is very much larger than the collector current. Thus, both assertion and reason is false.

Assertion: A N type semiconductor has a large number of electrons but still it is electrically neutral. Reason: A N type semiconductor is obtained by doping an intrinsic semiconductor with a pentavalent impurity.

Which of the following logic gate has only one input and one output?

In a full wave rectifier in which input voltage is represented by V = Vₘ sin ωt, then peak inversion voltage of non conducting diode will be:

A specimen of silicon is to be made P⁻type semi-conductor for this one atom of indium, on an average, 5×10⁷ silicon atoms. If the number density of silicon is 5×10²² atom/m³. Then the number of acceptor atom per cm³ will be

A semiconductor has an electron concentration of 8×10¹³ per cm³ and a hole concentration of 5×10¹² per cm³. The electron mobility is 25000 cm²V⁻¹s⁻¹ and the hole mobility is 100 cm²V⁻¹s⁻¹. Then,

The proper combination of 3 NOT gate and 1 NAND gate is shown. If $A = 0, B = 1, C = 1$ then the output of the combination is,

The logic circuit as shown below has the input waveform A and B as shown pick out the correct output waveform.

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

A semiconductor having electron and hole mobilities $\mu_n$ and $\mu_p$ respectively. If its intrinsic carrier density is $n_i$, then what will be the value of hole concentration $P$ for which the conductivity will be minimum at a given temperature?

In an intrinsic semiconductor band gap is 1.2 eV then ratio of number of charge carriers at 600 K and 300 K is

Given that the mobility of electrons in Ge is 0.4 m² V⁻¹ s⁻¹ and electronic charge is 1.6 × 10⁻¹⁹C. The number of donor atom (per m³) semiconductor of conductivity 500 mho/m is

The circuit as shown in figure, the equivalent gate is

Which of the following current must be zero in an unbiased PN junction diode?

In the given circuit, the voltage across the load is maintained at 12 V. The current in the zener diode varies from 0-50 mA. What is the maximum wattage of the diode?

For a common-emitter transistor, input current is 5 μA, β = 100 circuit is operated at load resistance of 10 kΩ, then voltage across collector emitter will be

Direction of electric field in P⁻N junction diode is

Assertion : Photodiode and photovoltaic cell are based on the same principle. Reason : Both use same method of operations to work.

Assertion : Transistor can be used as a switch. Reason : Both linear and non-linear voltage bias dependance occurs in it.

The logic gate represented in following figure is

Assertion: A pure semiconductor has negative temperature coefficient of resistance. Reason: On raising the temperature, more charge carriers are released, conductance increases and resistance decreases.

Assertion: At a fixed temperature, silicon will have a minimum conductivity when it has a smaller acceptor doping. Reason: The conductivity of an intrinsic semiconductor is slightly higher than that of a lightly doped p-type.

When the inputs of a two input logic gate are 0 and 0, the output is 1. When the inputs are 1 and 0, the output is zero. The type of logic gate is

Assertion : A photocell is called an electric eye. Reason : When light is incident on some semiconductor its electrical resistance is reduced.

If collector current is 120 mA and base current is 2 mA and resistance gain is 3, what is power gain?

Zener diode acts as a/an

In the half wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be

A transistor is a/an

Assertion : NAND is a universal gate. Reason : It can be used to describe all other logic gates.

When a p-n diode is reverse biased, then

The circuit given below represents which of logic operations?

A light emitting diode (LED) has a voltage drop of 2 volt across it and passes a current of 10 mA when it operates with a 6 volt battery through a limiting resistor R. The value of R is

The minimum potential difference between the base and emitter required to switch a silicon transistor ON is approximately

Given below is the circuit diagram of an AM demodulator. For good demodulation of AM signal of carrier frequency f, the value of RC should be

Assertion : A p-n junction with reverse bias can be used as a photo-diode to measure light intensity. Reason : In a reverse bias condition the current is small but is more sensitive to changes in incident light intensity.

Which of the following logic gates is an universal gate?

In a semiconducting material the mobilities of electrons and holes are μₑ and μₕ, respectively. Which of the following is true?

The voltage gain of the following amplifier is

The circuit shown below acts as

Assertion : A diode lasers are used as optical sources in optical communication. Reason : Diode lasers consume less energy.

Assertion : The logic gate NOT can be built using diode. Reason : The output voltage and the input voltage of the diode have 180° phase difference.

Assertion : The number of electrons in a p-type silicon semiconductor is less than the number of electrons in a pure silicon semiconductor at room temperature. Reason : It is due to law of mass action.

Assertion : In a common emitter transistor amplifier the input current is much less than the output current. Reason : The common emitter transistor amplifier has very high input impedance.