Monday, 8 May 2023

PhD entrance examination – 2023 Subject: Physics

 

PhD entrance examination – 2023 April

Subject: Physics

1. The Lagrangian equation of motion are _____ order differential equations

A) First                                    B) Second                               C) Third                                  D) Fourth

 

2. The Richardson constant value with unit is

A) 1.2 × 106 Am-2 K                                                                           B) 1.02 × 106 Am-2 K 

C) 1.21 × 106 Am-2 K                                                              D) None of these

 

3. Quantum dot is a ______ entity

A) 3-dimensional                    B) 2-dimensional                     C) 1-dimensional                     D) 0-dimensional

 

4. Which one of the following is not a type of LCD display?

A) Twisted Nematic                                                               B) In-Plane Switching 

C) Edge lit                                                                              D) Vertical alignment

 

5. In the inverse piezoelectric effect, ______ waves are produced.

A) Electromagnetic                 B) Infrasonic                           C) Ultrasonic                         D) Micro

 

6. A thermodynamic process in which pressure remains constant is called

A) Isobaric                             B) Isothermal                          C) Isotropic                             D) Isocyclic

 

4. Poisson bracket is useful to find the

(a) Integrals of motion

(b) Equations of motion

(c) Lagrange function

(d) Hamilton’s function

7. Poisson bracket is useful to find the

A) Integrals of motion                                                           B) Equations of motion

C) Lagrange function                                                              D) Hamilton’s function

 

8. APD is a photodiode where A stands for

A) Advanced                          B) Aerial                                 C) Atomic                               D) Avalanche

 

9. The reason for narrow tube in He-Ne laser

A) Atomic collision with tube wall increases                       B) Atomic collision with tube wall decreases

C) There is no effect of narrow tube on He-Ne                      D) None of these

 

10. Erbium doped fibers have long _________ leading to coherent amplification.

A) Edges                                 B) Metastable states              C) Connectors                         D) None of these

 

11. Which of the following is described by the concept of numerical aperture in an optical fiber?

A) Light scattering                  B) Light collection                 C) Light deviation                  D) Light polarization

 

12. If uncertainty in the position of an electron is zero, the uncertainty in its momentum will be

A) <h/4𝜋                                 B) >h/4𝜋                                 C) zero                                                D) infinite

13. The Andromeda galaxy is which of the following types of galaxies?

A) Elliptical                             B) Spiral                                 C) Barred-spiral                      D) Irregular

 

14. Light signals are transmitted through optic fibers by

A) Multiple total internal refraction                                        B) Birefringence        

C) Dispersion                                                                          D) None of these

 

15. Which among the following is a dielectric?

A) Copper                               B) Aluminium                         C) Plastic                                 D) Ceramic

 

16. Which of the following waves/rays are produced by nuclear changes in the atom?

A) Infrared rays                      B) Ultrasonic waves                C) Gamma rays                     D) X-rays

 

17. The correct sequence of the following materials in the increasing order of magnetic susceptibility is

A) Diamagnetic – Ferromagnetic – Paramagnetic – Superconductor

B) Ferromagnetic – Paramagnetic – Diamagnetic – Superconductor

C) Paramagnetic – Diamagnetic – Superconductor – Ferromagnetic

D) Superconductor – Diamagnetic – Paramagnetic – Ferromagnetic

 

18. At high temperatures, a ferromagnet becomes

A) Diamagnet                                                                         B) Soft Ferromagnet  

C) Paramagnet                                                                     D) Hard Ferromagnet

 

19. If the momentum of an object increases by 20%, its kinetic energy will increase by,

A) 66%                                    B) 77%                                    C) 44%                                   D) 55 %

 

20. Which of the following will NOT show electron spin resonance (ESR)?

A) Free radicals                                                                       B) Paramagnetic materials

C) Transition metals                                                                D) Diamagnetic materials

 

21. When electrons are trapped in the crystal lattice in place of anion vacancy, the defect in the crystal is known as

A) Non-stochiometric defect                                                  B) Stochiometric defect         

C) F-centre                                                                             D) Frenkel defect

 

22. Which of the following factors is the self inductance associated with a coil is independent of?

A) Induced voltage                 B) Current                               C) Time                                   D) Coil resistance

 

23. A ferroelectric crystal loses spontaneous polarization at

A) Transition temperature                                                       B) Fermi temperature

C) Curie temperature                                                           D) Debye temperature

 

24. Two tuning forks when sounded together produced 4 beats/sec. The frequency of one fork is 256. The number of beats heard increases when the fork of frequency 256 is loaded with wax. The frequency of the other fork is

A) 504                                     B) 520                                     C) 260                                     D) 252

 

25. Which one of the following set of gates are best suited for parity checking and parity generation?

A) AND, OR, NOT Gates                                                      B) NOR Gates                                   

C) NAND Gates                                                                     D) EX-NOR or EX-OR Gates

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