Biju Patnaik University of Technology 2008-2nd Sem B.Tech (B Tech) , physics-I . - Question Paper
BPUT(B Tech) , second semester physics-I ques. paper. Total number of printed pages -8 B, Tech BSCP 2101
Second Semester Examination - 2008 PHYSICS -1
Full'Marks-70 Time:3 Hours
Answer Question No. 1 which is compulsory and any five from the rest.
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The figures in the right hand margin Indicate marks for the questions.
Total number of printed pages -8 B, Tech BSCP 21011, Answer the following questions: 2x10
(a) Two waves each of equal amplitude and equal frequency pass through a point in the medium in ihe same direction with phase difference 60. Calculate the amp/itude of the resuJtanl wave at this poim.
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(b) Newtons ring experiment was conducted first in air medium then in water medium (i.e. water is inserted in between the plano-convex tens and glass plate.) What happens to the diameter of a particular ring ?
(c) A particle is trapped in an infinite deep potential well has de Broglie wavelength X in the ground state. What is the wavelength of the particle in the next excited state ?
(d) In a Ntcol prism he and Ho are the refractive indices for E-ray and O-ray respectively, lf1(MB is the refractive index of the Canada balsam, write a relation between He. Ho and hb.
(e) In single slit diffraction pattern orange tight is replaced by red light without changing the experimental setup. What will happen to the diffraction pattern ?
(f) The parallel plate capacitor has plates each of area 2m2 and the plates are separated by a dielectric of thickness 1 mm, dielectric constant 3. The potential difference and conduction current in the connecting wire at certain instant of time is 100 V and 2 mA respectively. Find out the displacement current flowing between the two plates of the capacitor.
(g) Prove that plasma frequency is approximately equal to 9%/N. where 'Nf is the electron density in the plasma medium.
(h) Write down the time independent Schrodingers equation for a free particle of mass m and energy E moving in XY-plane
(i) Compute the de Broglie wavelength of bike having mass 100kg and moving with speed 100km/hour.
(j) E*platn wfiy n potential step pfobkifti time independent Schr6dmgers equatroo is laKon
? fa) Givr* ai comparison between conduction ctmni and displacement current 3
(bj Gwe a gfaphical comparison among the following four types oi harmonic motions.
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{i) Simple harmonic motion (jfj Under damped harmonic molion (ui) Over damped harmonic motion (iv) Critically damped harmonic molion.
(c) How you will know with naked eye the given specimen is an ordinary glass piece or a grating ? 2
id) critical angle in certain substance is given to be 42. Calculate Ihe polarizing angle 2
3- (a) What is the color of Ihs central I ring in Young double slit experimenl when, while Ughl source is used 2
lb) The electric vector component of a plane electromagnetic vector propagating in a noninagnetkC medium is given by
I v 60 cos{l0*t +2 z)V/m Symbots have their usual meanings. Find' the relative
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pernuttivjty of ihe medium and magnetic
vector component ol ihe wave. 4
fc) What do you mean by wave function ? What are the character Stic of wave function of matter wave ? 7+3
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4. (a) Explain ihe presence of only odd numbered foci a zone plate. 3"
{b) The shapes of the interference fringes obtained in Young's double slit experiment are actually hyperbolae. Derive an approxsmateexpression for eccentricity of tha hyperbolic fripge, 5
(c) The electric component'vector of a 'plane electromagnetic wave propagating in a nonmagnetic medium is given by E = p 40 cos{10*4 +4z)V/m. Find the direction of propagation. 2
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5. (a) Describe in detail the construction and
working of a Laurent's half-shade pola-rimeter. Explain how you would use it to determine the specific rotation of sugar solution. 6
(b) An electron is trapped completely in a one dimensional region of width 1 X. How much energy must be supplied to excite the electron from ground state to first excited state ? 2
(c) How does quantum physics differs from classical physics imipotential step problems.
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6. (a) In Newtoms ring experiment in laboratory
sodium vapor lamp having two wavelengths 5890 A and 5896 X is used, if it is found that nth dark ring due to 5860 X
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coincides with {n+2)nd dark ring due to 5890 X, then calculate the radii of nth dark rings due to 5896 A and 5890A. The radius of curvature of the planoconvex lens used is 200 cm. 4
(b) Explain how displacement and velocity graph of a simple harmonic oscillator is elliptical. 3
(c) Derive a relation between magnitudes of electric vector and magnetic vector. 3
7. (a) A sodium vapour light containing two wavelengths 5890 X and 5890 X is incident normally on a plane transmission grating having 15000lines/ inch. A lens of focal length 100 cm is used to observe the spectrum on a screen. Calculate the distance between the two lines in the first order spectrum. 5
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(b) How can you get a scalar function from a vector field and how can you get a vector function from a scalar field ? Give physical examples of both the cases. 3
(c) An electromagnets wave is propagating
m a medium m such a manner lhal etectnc vector of the wave satisfies the differences
tial wave equation v2 E ui How
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much energy wilt be absort>ed by the medium in 20 seconds ? 2
8. (a) If m ts refractive index of a potential step for the case E > V0 then prove that the transmission coefficient for the incident
particles
(b) What is the physical significance of gradient of a scalar function ? 2
(c) Two simple harmonic oscillators of different masses oscillate separately under the action of same restoring force at frequencies 3Hz and 5Hz. Calculate the ratio of their masses, 2
(d) Distinguish between plane of polarization and plane of vibration. 2
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