UPSC Physics Optional PYQs (CSE & IFoS)PYQs

Distinguish between a normal conductor, a superconductor and a semiconductor. How a p-type semiconductor differs from an n-type?

Describe the phenomenon of Meissner effect and its importance in the study of superconductors.

Give an elementary outline of high-temperature superconductors and their experimental status.

Give schematic diagrams to distinguish between n\text{-}p\text{-}n and p\text{-}n\text{-}p transistors.

What are logic gates and truth tables? Obtain the truth table of a two-input OR gate.

The primitive translation vectors of a two-dimensional lattice are \hat{a}=2\hat{i}+\hat{j},\quad \hat{b}=2\hat{j}. Determine the primitive translation vectors of its reciprocal lattice.

What is the difference between direct and indirect band gap semiconductors? Which one is suitable for use in solar cells?

Describe the following laws of Boolean algebra with one application each to logic circuit :

(i) Commutative law of addition

(ii) Associative law of addition

(iii) Associative law of multiplication

(iv) Distributive law

Obtain Laue's equations for X-ray diffraction by crystals. Show that these are consistent with the Bragg's law.

Distinguish between diamagnetic, paramagnetic and ferromagnetic substances.

With the help of a schematic diagram, show how entropy and specific heat vary with temperature for a superconductor.

Explain the operation of NOR gate with a logical diagram and truth table. Show how NOR gate can be used as Universal gate.

What are called intrinsic and extrinsic semiconductors ?

Explain the term critical magnetic field in a superconductor. How does the critical magnetic field vary with temperature in Type-I and Type-II superconductors ? What is Meissner effect ?

Construct the following function with logic gates : Y = (A + B) (C + D + E) (F + G + H + I) (JKL)

With a suitable circuit diagram and theory explain the use of OP-Amps as

(i) Adder, and

(ii) Integrator.

Simplify the logical expression [A\bar{B}(C+BD)+\bar{A}\bar{B}]C.

Describe an operational amplifier based integrator. Using operational amplifier integrators, design a circuit to solve the following differential equation: \frac{d^2v}{dt^2}+2\frac{dv}{dt}+3v=0

Design a transistor based Colpitt oscillator which can oscillate at 9\,\mathrm{MHz}. Explain how the oscillations are created and sustained.

Differentiate between n-p-n and p-n-p transistors. Give their device structure and biasing circuits when used as an amplifier.