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CBSE

#1 Class 12 Physics Semiconductor 2022 Short 2M

Which device is used to convert AC into DC? State its underlying principle and explain its working. If the frequency of input AC is 60 Hz, what will be the frequency of the output?

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#2 Class 12 Physics Semiconductor 2023 Long 4M

Case Study on p-n junction diode: (I) If Ge and Si diodes start conducting at 0.3 V and 0.7 V respectively and Ge diode connections are reversed, how does $V_0$ change? (II) A diode circuit: find $V_0$ and $I_d$. (III...

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#3 Class 12 Physics Semiconductor 2023 Long 4M

Case Study on LED: (i) Why are LEDs made of compound semiconductors and not elemental semiconductors? (ii) What should be the order of bandgap of an LED to emit light in the visible range? (iii) A student connects a b...

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#4 Class 12 Physics Semiconductor 2022 Short 2M

In the graph of potential barrier versus width of depletion region for an unbiased diode (Graph A), graphs B and C are obtained after biasing. Identify the type of biasing in B and C and justify your answer.

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#5 Class 12 Physics Semiconductor 2021 Short 2M

The circuit has a pure semiconductor $S$ in series with a variable resistor $R$ and a constant voltage source $V$. Should $R$ be increased or decreased to keep the ammeter reading constant when $S$ is heated? Justify.

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#6 Class 12 Physics Semiconductor 2023 Long 5M

Explain the band theory of solids. State how solids are classified into conductors, insulators and semiconductors on this basis.

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#7 Class 12 Physics Semiconductor 2021 Short 2M

The circuit has two oppositely connected ideal diodes in parallel. Find the current through each diode in the circuit. (Battery = 12 V; $R_1 = 4\ \Omega$, $R_2 = 3\ \Omega$, $R_3 = 2\ \Omega$ with D1 and D2 in branches.)

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#8 Class 12 Physics Semiconductor 2022 Long 5M

Draw the circuit diagram of a full-wave rectifier using p-n junction diodes. Explain its working and show the output and input waveforms.

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#9 Class 12 Physics Semiconductor 2021 Short 3M

Name the important process that occurs during formation of a p-n junction. Explain how a p-n junction is formed. Define barrier potential.

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#10 Class 12 Physics Semiconductor 2022 Long 5M

Explain, with the help of a circuit diagram, the working of a p-n junction diode as a half-wave rectifier.

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#11 Class 12 Physics Semiconductor 2022 Short 3M

Draw V-I characteristics of a p-n junction diode. Answer: (i) Why is the reverse current almost independent of applied potential up to a critical voltage? (ii) Why does reverse current show a sudden increase at critic...

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#12 Class 12 Physics Semiconductor 2021 Short 2M

Draw the energy band diagram of (a) n-type and (b) p-type semiconductor at temperature $T > 0$ K. Mark the donor and acceptor energy levels with their energies.

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#13 Class 12 Physics Semiconductor 2020 Short 2M

Distinguish between n-type and p-type semiconductors.

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#14 Class 12 Physics Semiconductor 2021 Short 2M

Pure Si at 500 K has equal electron and hole concentration $n_i = 1.5 \times 10^{16}$ m$^{-3}$. Doping by indium increases $n_h$ to $4.5 \times 10^{22}$ m$^{-3}$. Identify the type of doped semiconductor and find the ...

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#15 Class 12 Physics Semiconductor 2022 Long 1M

Assertion (A): Putting p-type semiconductor slab directly in physical contact with n-type semiconductor slab cannot form a p-n junction. Reason (R): The roughness at the contact will be much more than inter-atomic cry...

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#16 Class 12 Physics Semiconductor 2022 Mcq 1M

The number of electrons made available for conduction by dopant atoms depends strongly upon

A. doping level

B. increase in ambient temperature

C. energy gap

D. both doping level and temperature

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#17 Class 12 Physics Semiconductor 2023 Long 1M

Assertion (A): The electrical conductivity of a semiconductor increases on doping. Reason (R): Doping always increases the number of electrons in the semiconductor.

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#18 Class 12 Physics Semiconductor 2022 Long 1M

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

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#19 Class 12 Physics Semiconductor 2021 Long 1M

Assertion: The value of current through p-n junction in the given figure will be 10 mA. Reason: In the above figure, p-side is at higher potential than n-side.

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#20 Class 12 Physics Semiconductor 2022 Long 1M

Assertion: The resistivity of a semiconductor decreases with temperature. Reason: The atoms of a semiconductor vibrate with larger amplitude at higher temperatures, thereby decreasing its resistivity.

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