PYQ Bank

How do thermistors and solar cells differ in structure and operation?

What are the differences in electrical characteristics of FET (JFET) and MOSFET?

Consider an energy band which is filled with electrons up to a certain value k_1 \left(k_1 < \frac{\pi}{a}\right). Determine the total effective number of free electrons in the energy band. Comment on the electron distribution in an insulator, intrinsic semiconductor and metals at 0\text{ K}. Symbols have their usual meanings.

What is X-ray diffraction? How is an XRD pattern used to determine the crystal structure of the material?

Find the radius of the interstitial sphere which can just fit into the void at the body centre of the \text{fcc} structure coordinated by the facial atoms.

In powder diffraction method pattern for lead with radiation of wavelength \lambda = 1\cdot 54 \text{ \AA}, the (220) Bragg reflection angle is \theta = 32^\circ. Find the radius of the atom.

Explain the cause of hysteresis phenomenon in ferromagnetic materials. What does the area of the hysteresis loop signify?

Classify diamagnetic, paramagnetic and ferromagnetic materials in terms of their magnetic susceptibility (\chi). Plot and explain the variation of \frac{1}{\chi} with temperature for the three materials.

(i) Give a qualitative description of the BCS theory and explain how it accounts for the superconducting state. (ii) The critical field of niobium is 1 \times 10^5\text{ A/m} at 8\text{ K} and 2 \times 10^5\text{ A/m} at absolute zero. Find the transition temperature of the element.

Describe the bandwidth and slew rate of an Op-Amp. The amplifier shown in the below circuit is used to amplify an input signal to a peak output voltage of 100\text{ mV} and its slew rate is 0\cdot 5\text{ V}/\mu\text{s}. What is the maximum operating frequency of the amplifier?

The total binding energies of {}_8^{15}\text{O}, {}_8^{16}\text{O} and {}_8^{17}\text{O} are 111\cdot 96 \text{ MeV}, 127\cdot 62 \text{ MeV} and 131\cdot 76 \text{ MeV} respectively. Determine the energy gap between 1p_{1/2} and 1d_{5/2} neutron shells for the nuclide whose mass number is close to 16.

By considering a suitable nuclear potential well for the deuteron ground state, show that it is a loosely bound nucleus.

\rho^0 and \text{K}^0 mesons both decay mostly to \pi^+ and \pi^-. Why the mean lifetime of \rho^0 is 10^{-23} \text{ s}, whereas that of \text{K}^0 is 0\cdot 89 \times 10^{-10} \text{ s}?

(i) \pi^- \rightarrow \mu^- + \bar{\nu}_\tau (ii) n \rightarrow p^+ + e^- + \bar{\nu}_e Explain the various leptonic family members. What is leptonic number conservation? Based on this conservation law, tell whether the following reactions are possible or not : (i) \pi^- \rightarrow \mu^- + \bar{\nu}_\tau (ii) n \rightarrow p^+ + e^- + \bar{\nu}_e

Calculate the minimum energy (E_\gamma) required for a gamma ray photon to disintegrate a deuteron of mass M and binding energy B into a neutron and a proton. (Assume B \ll Mc^2)

What is the minimum energy required to break a {}_2^4\text{He} nucleus into free protons and neutrons? [ Given, m_{\text{H}} = 1\cdot 007825 \text{ amu}, m_n = 1\cdot 008665 \text{ amu}, m_e = 0\cdot 00055 \text{ amu} and m_{\text{He}} = 4\cdot 002603 \text{ amu} ]

Consider a uranium nucleus ({}_{92}\text{U}^{236}) breaking up spontaneously into two equal parts. Estimate the reduction of electrostatic energy of the nucleus considering uniform charge distribution. [ Assume that nuclear radius is 1\cdot 2 \times 10^{-13} A^{1/3} \text{ cm} ]

State the basic assumption of single-particle shell model. How do the centrifugal and spin-orbit terms remove the degeneracy of three-dimensional spherical harmonic oscillator?