## Engineering Physics - Dec 2014

### First Year Engineering (Set B) (Semester 1)

TOTAL MARKS: 100

TOTAL TIME: 3 HOURS
(1) Question 1 is compulsory.

(2) Attempt any **four** from the remaining questions.

(3) Assume data wherever required.

(4) Figures to the right indicate full marks.

### Answer the any one question from Q1 & Q1 (e)

**1 (a)** What do you understand by wave function, discuss its physical significance?(2 marks)
**1 (b)** State and explain Heisenberg?s uncertainty principle. Explain diffraction of electron beam by a single slit to illustrate this principle.(2 marks)
**1 (c)** The uncertainty in measuring the speed of an accelerated electron is 1.2?10^{5} m/s. Calculate the uncertainty in finding its location, while it is still in motion. Given h=6.626?10^{?34} Js and Mass of electron=9.31?10^{?31} kg.(3 marks)
**1 (d)** What is meant by operators? Obtain an operator for the energy ?E?, momentum ?p? and use them to obtain Schrodinger wave equation.(7 marks)
**1 (e)** Define particle velocity, group velocity and phase velocity and derive the relation between them.(14 marks)

### Answer the any one question from Q2 & Q2 (e)

**2 (a)** Explain the difference between interference and diffraction of light.(2 marks)
**2 (b)** State Brewster?s law and prove that at Brewster?s angle the reflected and refracted rays are perpendicular to each other.(2 marks)
**2 (c)** In Newton?s ring experiment the diameter of 15^{th} dark ring was found to be 0.59 cm and that of the 5^{th} ring was 0.336 cm. If the radius of curvature of plano-convex lens is 100 cm. Calculate the wavelength of light used.(3 marks)
**2 (d)** Explain the formation of Newton?s ring in reflected light. Prove that in reflected light [ D_n propto sqrt{n} and D_n propto sqrt{2n+1} ] where D_{n} and D'_{n} is diameter of dark and bright ring respectively.(7 marks)
**2 (e)** Discuss the phenomena of Fraunhofer diffraction at double slit. Derive the condition for maxima and minima for double slit diffraction pattern.(14 marks)

### Answer the any one question from Q3 & Q3 (e)

**3 (a)** Why do we say that the nucleus behaves like a liquid drop?(2 marks)
**3 (b)** What do you understand by mass defect and binding energy with respect to the nucleus?(2 marks)
**3 (c)** The radius of Cyclotron dee's is 40 cm and magnetic field is 1.5 Wb/m^{2}. What is the maximum kinetic energy of beam of proton accelerated by the Cyclotron? Given mass of proton=1.67×10^{-27} kg and Charge on Proton = 1.6×10^{-19} C.(3 marks)
**3 (d)** Explain construction, principle of working and limitations of LINAC. In LINAC show that the length L_{n} of the n^{th} drift tube is proportional to √n.(7 marks)
**3 (e)** Discuss the construction and working of Cyclotron with neat diagram. Derive and explain resonance condition.(14 marks)

### Answer the any one question from Q4 & Q4 (e)

**4 (a)** Superconductor is a perfect diamagnetic. Explain briefly.(2 marks)
**4 (b)** What is Zener breakdown. Explain briefly(2 marks)
**4 (c)** A n-type semiconductor specimen has Hall coefficient R_{H}=3.66×10^{-4} m^{3}/C. The conductivity of specimen is found to be 112 ohm^{-1} m^{-1}. Calculate the charge carrier density and electron mobility at room tempertature.(3 marks)
**4 (d)** What is Hall effect? Deduce expression for Hall coefficient and Hall voltage of a solid. What important information's are obtained from its measurement?(7 marks)
**4 (e)** State and explain the terms dielectric polarization and Gauss's law. Derive the interrelationship between E, P and D vectors.(14 marks)

### Answer the any one question from Q5 & Q5 (e)

**5 (a)** What is meant by stimulate emission? Explain the basic condition in which stimulated emission dominated.(2 marks)
**5 (b)** Differentiate between Step Index and Graded Index optical fiber cable.(2 marks)
**5 (c)** A glass clad fiber has cladding refractive index 1.49925 and fractional refractive index of 0.0005. Determine the critical internal reflection angle.(3 marks)
**5 (d)** Explain the construction and working of Ruby LASER with necessary energy level diagram.(7 marks)
**5 (e)** Describe the construction of an optical fiber. Explain the principle of propagation of light waves within a fiber. Define acceptance angle, acceptance cone and numerical aperture..(14 marks)