UPSC Physics Optional PYQs (CSE & IFoS)PYQs

Find the Boolean algebra expression for the above system.

Why does the resistance of a semiconductor decrease with increase in temperature ?

Explain with the help of a neat diagram the working of an RC coupled common emitter amplifier.

Define the terms critical magnetic field and critical temperature in a superconductor. Find the magnetic field strength necessary to destroy the superconductivity in a sample of lead at 4\cdot2\text{ K}. The critical magnetic field at 0\text{ K} is 0\cdot80\text{ Tesla} and the critical temperature is 7\cdot2\text{ K}.

Determine the values of emitter current and the collector current of the transistor having \alpha = 0\cdot98 and collector to base leakage current I_\text{CBO} = 4\ \mu\text{A}. The base current is 50\ \mu\text{A}.

What do you understand by spontaneous magnetization below Curie temperature ? Explain with an appropriate diagram, the occurrence of a hysteresis loop in a ferromagnetic material.

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

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

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

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

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

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

Distinguish between diamagnetic, paramagnetic and ferromagnetic substances.

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

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

(i) Adder, and

(ii) Integrator.

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

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 ?

What are called intrinsic and extrinsic semiconductors ?

What is ac Josephson effect ? Derive an expression for the current flowing through the junction formed by two superconducting films separated by an insulator.

For the logical equation given below, form the truth table and draw the corresponding logic circuit using different gates : Y = A \cdot B + \overline{A \cdot B}