Engineering Physics — Winter 2019

Objective Question (MCQ) Mark

07 1. The polarization of a solid which contains Nnumber of particles per unit volume is equal to

P = NαE (b) P = 2NαE e e

P = Nα2E (d) P = Nα2E2 e e 2. SQUID is an application of

Semiconducting materials (b) Nano materials

Superconducting materials (d) Bio materials 3. In Nd:YAG LASER ___________ kind of pumping is used.

inelastic atomic collision (b) optical pumping

direct electron excitation (d) none of these 4. The following are the structure of CNT

Chiral (b) Zigzag

Armchair (d) all of these 5. Hysteresis loop for hard ferromagnetic substances is___________.

broad (b) narrow

cannot say (d) none of these 6. The high temperature stable phase of SMA is called

Austenite (b) Martensite

Nitiosite (d) None of these 7. SONAR means ________________.

Sound Negative and Ranging (b) Sound Navigation and Radiation

Sound Negative and Radiation (d) Sound Navigation and Ranging

07 1. Which Of the following is Weber-Fechner’s Law?

L = Klog I (b) I = Klog L1010

L2 = Klog I (d) I2 = Klog L1010 2. The current require to destroy the superconductivity is equal to

I = 4πr2H (b) I = 2πrH C C C C

I = 2πH (d) I = 2πrH C C C 0 3. Dielectric materials can also be termed as

Conductors (b) Semiconductors

Insulators (d) Superconductors 4. Which one is not having permanent dipoles in absence of magnetic field?

Paramagnetic material (b) Ferromagnetic material

Ferrimagnetic material (d) Diamagnetic material 5. LASER light consists of ________________.

Electron flow (b) Cosmic rays

UV rays (d) Coherent photons 6. ______________ is the process to synthesize Metallic Glass.

ball milling (b) CVD

plasma arching (d) melt spinning technique 7. NDT means ________________.

Nano Density Test (b) Nano Detection Test

Non Demanding Test (d) Non Destructive Test

Calculate the electronic polarisability of an isolated Se atom. The atomic radius of a Se atom is 0.12 nm. Given ε = 8.85 × 10-12 F/m.0

Explain important properties of superconducting materials.

List various polarization mechanisms in dielectric materials. Derive an expression for atomic polarizability α . e

Amagnetic material has a magnetization of 2300 Am-1 and produces a flux density of 0.00314 Wbm-2. Calculate the magnetizing force and the relative permeability of the material. Given permeability of the free space = 4π × 10-7 H/m.

Give the properties and applications of dielectric materials.

Write general properties of diamagnetic, paramagnetic and ferromagnetic materials.

The ultrasonic pulse echo method is employed to detect possible defects in a steel bar of thickness 40 cm. If the pulse arrival times are 40 µs and 80 µs, find the distance of defect from the end of the bar at which the ultrasonic pulse enters the bar.

What is the principle of magnetic recording? Discuss magnetic storage in magnetic hard disk.

What are the factors affecting acoustics of the buildings and their remedies?

The critical temperature for a metal with isotopic mass 199.5 is 4.185 K. Calculate the isotopic mass if the critical temperature falls to 4.133 K.

Explain the classification of optical fibres based on refractive index profile.

Describe the construction and working of Nd:YAG LASER with a suitable energy level diagram.

An optical fibre has a numerical aperture of 0.20 and a cladding refractive index of 1.55. Determine the acceptance angle for the fibre in water which has a refractive index of 1.33.

Write short note on Lithium cell.

List out techniques used in synthesis of Nanomaterials. Discuss any two of them in detail.

What should be the total absorption and average absorption coefficient in a hall of volume 10000 m3 and total surface are of 1400 m2 if it is required to have reverberation time of 1.4 seconds.

Write note on electron confinement.

Explain temperature induced and stress induced transformation in SMA in details.