**Applied Physics 1 question papers Mumbai university** – This is a collection of eight question papers which are unsolved for Mumbai University first year Applied Physics from 2016 backdated for revision.Thee question papers can be used by students of all branches of engineering for practice and is enough to clear the paper if you solve these questions.

### Applied Physics 1 question papers Mumbai university

## MAY 2016

Attempt any five from the following

1(a) Draw (a) (1 1 2) (b) (0 4 0) (c) [0 4 0] with reference to a cubic unit cell

3 M

1(b) What is the probability of an electron being promoted to the conduction band in diamond at 27°C, if the bandgap is 5.6 eV wide?

3 M

1(c) Define drift current, diffusion current and mobility of charge carriers.

3 M

1(d) What is dielectric polarization and dielectric susceptibility? Write the relation between them.

3 M

1(e) State and explain Ohm’s law in magnetic circuit.

3 M

1(f) Write Sabine’s formula and explain the terms used in it.

3 M

1(g) Calculate the length of an iron rod which can be used to produce ultrasonic waves of 20kHz Given – Y = 11.6 × 10

^{10}N/m^{2}, ? = 7.23 × 10^{3}kg/m^{3}3 M

2(a) Explain formation of energy bands in solids and explain classification on the basis of energy band theory.

8 M

2(b) Zn has hcp structure. The nearest neighbour distance is 0.27 nm. The atomic weight of Zn is 65.37. Calculate the volume of unit cell, density and atomic packing fraction of Zn.

7 M

3(a) What is hysteresis? Draw a hyteresis for ferromagnetic material and explain various important parameters.

A magnetic material has a magnetization of 2300 A/m and produces a flux density of 0.00314 wb/m

A magnetic material has a magnetization of 2300 A/m and produces a flux density of 0.00314 wb/m

^{2}, Calculate magnetizing force and permeability of the material.8 M

3(b) Explain the statement ‘crystal act as three dimesional grating with X-rays’.

Monochromatic X-ray beam of wavelength &lambda = 5.8189 A° is reflected strongly of lattice constant 3A°. Determine Miller indices of the possible reflecting planes.

Monochromatic X-ray beam of wavelength &lambda = 5.8189 A° is reflected strongly of lattice constant 3A°. Determine Miller indices of the possible reflecting planes.

7 M

4(a) Define ligancy. Find the value of critical radius ratio for ligancy 4.

5 M

4(b) An impurity of 0.01 ppm is added to Si. The semiconductor has a resistivity of 0.25?m at 300K. Calculate the hole concentration and its mobility. Atomic weight of Si is 28.1, density of Si=2.4×10

^{3}kg/m^{3}5 M

4(c) Explain the origin of electronic, ionic and orientational polarization and temperature dependence of respective polarizability.

5 M

5(a) The density of copper is 8980kg/m

^{3}and unit cell dimension is 3.61 A°. Atomic weight of copper is 63.54. Determine type of crystal structure. Calculate atomic radius and interplanner spacing of (1 1 0) plane.5 M

5(b) What is Hall effect? Derive expression for Hall voltage with neat labelled diagram.

5 M

5(c) Explain how the reverberation time is affected by (i) size (ii) nature of wall surface (iii) audience in an auditorium.

5 M

6(a) Estimate the ratio of vacancies at (i) -119°C (ii) 80°C where average required to create vacancy is 1.8eV.

5 M

6(b) How a p-n junction diode is used to generate a potential, difference in a photovoltaic solar cell?

5 M

6(c) Explain with neat lebelled diagram the construction and working of a piezoelectric oscillator.

5 M

## DEC 2015

Attempt any five from the following:

1 (a) Draw the unit cell and Basic of DC structure.

3 M

1 (b) Draw the following w.r.t. a cubic unit cell:

(1 1 1) (1 1 1) (1 2 3).

(1 1 1) (1 1 1) (1 2 3).

3 M

1 (c) Draw a neat labelled Energy band diagram to show the variation of Fermi Level with doping concentration in N-Type semi-conductors.

3 M

1 (d) Calculate electronic polarizability of Argon atom. Given relative permittivity is 1.0024 at NTP and the gas contains 2.7 × 10

^{25}atoms per m^{3}.3 M

1 (e) What are the properties of soft magnetic materials? Briefly explain one application.

3 M

1 (f) Monochromatic high energy x-rays are incident on a crystal. If 1st order reflection is observed at an angle 3.4°, at what angle would 2nd order reflection be expected.

3 M

1 (g) A class room has dimensions 20 × 15 × 5 m

^{3}. The reverberation time is 3.5 sec. Calculate the total absorption of its surface and average absorption coefficient.3 M

2 (a) Draw the unit cell of HCP. Derive the number of atoms/ unit cell, the c/a ration and the packing fraction. Calculate the ratio of the number of vacancies to the number of atoms when the average energy required to create a vacancy is 0.95 ev at 500k.

8 M

2 (b) Explain Hall effect & its significance. With a neat diagram derive the expression for the hall voltage & Hall co-efficient.

7 M

3 (a) Draw the hysteresis loop for a ferromagnetic material. Prove that in a ferromagnetic material, the power loss / unit volume in a hysteresis cycle is equal to the area under the hysteresis loop.

A solenoid consisting of 500 turns and carrying 5amp is 0.5 long. Calculate (i) magneto motive force & (ii) Total flux if the area of the cross section in 0.0004 m

A solenoid consisting of 500 turns and carrying 5amp is 0.5 long. Calculate (i) magneto motive force & (ii) Total flux if the area of the cross section in 0.0004 m

^{2}. (Assume the medium is air).8 M

3 (b) With a neat labelled diagram explain the principle, construction and working of a piezoelectric oscillator.

7 M

4 (a) Explain analysis of crystal structure using Bragg’s X-ray spectrometer.

5 M

4 (b) An Ultrasonic beam of 1 cm wavelength sent by a ship returns from sea bed after 2 sec. If the salinity of sea water at 30°C is 29 gm/lit. Calculate the depth of sea bed at 30°C and the frequency of ultrasonic beam.

5 M

4 (c) Explain Critical Configuration & find the Critical radius ratio of an ionic crystal for ligancy 6.

5 M

5 (a) Explain ionic polarization & derive the expression for ionic polarizability.

5 M

5 (b) In a solid, consider the energy level lying 0.012ev below Fermi level. What is the probability of this level not being occupied by an electron?

Given T=300 Kelvin. K

Given T=300 Kelvin. K

_{s}=1.38×10^{-23}j/K.5 M

5 (c) For an intrinsic semiconductor show that the Fermi level lies in the center of the forbidden energy gap.

5 M

6 (a) What is reverberation? Define Reverberation time. Explain its role in acoustics.

5 M

6 (b) Explain the principle, construction & working of a LED.

5 M

6 (c) Describe the types of liquid crystal & their properties.

5 M

## MAY 2015

Attempt any five from the following:

1 (a) Draw the following in a cubic unit cell (0 1 2), (1 2 3), [1 2 1]

3 M

1 (b) Define the term space lattice, unit cell and lattice parameter.

3 M

1 (c) Determine the lattice constant for FCC lead crystal of radius 1.746 Å and also find the spacing of (2 2 0) plane.

3 M

1 (d) Define: drift current, diffusion current and mobility of charge carriers.

3 M

1 (e) What is the probability of an electron being thermally promoted to conduction band in diamond at 27°C, if bandgap is 5.6 eV wide.

3 M

1 (f) Why soft magnetic materials are used in core of transformers?

3 M

1 (g) Calculate the electronic polarizability of A

_{1}. Given number of Air atoms at NTP=2.7×10^{25}/m^{3}and dielectric constant of Ar=1.0024.3 M

2 (a) Show that for intrinsic semiconductors the Fermin level lies midway between the conduction band and the valence band. Draw the energy level diagram a function of temperature for n-type of semi-conductor.

8 M

2 (b) Cu has FCC structure. If the interplanar spacing d is 2.08 A° for the set of (111) planes. Find the density and diameter of Cu atom. Give atomic weight of Cu is 63.54.

7 M

3 (a) What is hysteresis? Draw a hysteresis loop for ferromagnetic material and explain the various important points on it. For a transformer which kind of material will you prefer-the one with small hysteresis area or the big one?

8 M

3 (b) Derive Bragg’s law. X-ray of unknown wavelength give first order Bragg’s reflection at glancing angle of 20° with (2 1 2) planes of cooper having FCC structure. Find the wavelength of X-rays, if the lattice constant for cooper is 3.615 A°.

7 M

4 (a) Discuss Diamond structure with neat diagram and also determine the effective number of atoms / unit cell, co-ordination number and atomic radius in tems of lattice constant.

5 M

4 (b) Classify solids on the basis of energy band diagram.

5 M

4 (c) Explain orientational polarization with suitable diagram and write the mathematical expression of orientational polarizability.

5 M

5 (a) Calculate the number of atoms per unit cell of a metal having the lattice parameter 2.9 A° and density 7.87 gm/cm

^{3}. Atomic weight of metal is 55.85. Avogadro number is 6.023×10^{23}/gm mole.5 M

5 (b) What is Hall effect? Mention its significance. How mobility can be determined by using Hall effect?

5 M

5 (c) The reverberation time is found to be 1.5 second, for an empty Hall and it is found to be 1.0 second when a curtain cloth of 20m

^{2}is suspended at the centre of the Hall. If the dimensions of the hall are 10×8×6m^{3}, calculate the coefficient of absorption of curtain cloth.5 M

6 (a) Describe principle, construction and working of magnetostriction oscillator to produce ultrasonic waves.

5 M

6 (b) Briefly explain the different types of point defects.

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6 (c) Explain how a voltage difference is generated in a p-n junction when it is used in a photovoltaic solar cell.

5 M

## DEC 2014

Solve any five of the following.

1(a) Identify the type of lattice and number of atoms per unit cell for CsCl and BaTiO

_{3}(above 120°C) crystal strcuture.3 M

1(b) Fermi Energy for Silver is 5.5 eV. Find out the energy for which the probability of occupancy at 300K is 0.9.

3 M

1(c) Explain the formation of depletion region in an unbiased p-n junction.

3 M

1(d) Write three distinct differences between ionic and oriental polarization.

3 M

1(e) Draw the variation of permeability against external magnetic field for a paramagnetic and ferromagnetic material (below Curie temperature)

3 M

1(f) Mention only one solution for each of the following acoustical problems in a hall. (i) Echo (ii) Dead spot and (iii) Inadequate loudness

3 M

1(g) What is piezoelectric effect? Why ferro-electrics are prefferred than quartz for the production of ultrasonic waves?

3 M

2(a)(i) What is effective mass? Why the effective mass of holes is more than the effective mass of electrons?

4 M

2(a)(ii) Draw the diagrams only (fully labelled and self explanatory) to show the variation of Fermi energy with (i) Temperature and (ii) Impurity concentration at high level, for an n-type semiconductor.

4 M

2(b) Define space lattice and basis. A metal crystallizes with a density of 2.7gm/cc and has a packing fraction of 0.74. Determine the mass of one atom if the nearest neighbour distance is 2.86Å.

7 M

3(a) Explain the variation in magnetic induction with magnetic field for a ferromagnetic material, using the domain theory and with the help of a graph. A magnetic field of 1800 Amp/m produces a magnetic flux of 3×10

^{-4}Wb in an iron bar of cross-sectional area of 0.2cm^{2}. Calculate the susceptibility and the permeability.8 M

3(b)(i) How the variation in glancing angle is achieved while determining the crystal structure using (i) Rotating crystal method and (ii) Powder method?

3 M

3(b)(ii) Calculate Bragg angle if (200) planes of a BCC crystal with lattice parameter 2.814Å give second order reflection with X-rays of wavelength 0.71Å.

4 M

4(a) Calculate the critical radius ratio of an ionic crystal in ligancy 4 configuration.

5 M

4(b) Determine the concentration of conduction electron in a sample of Silicon if one in every million Silicon atom is replaced by a Phosphorous atom. Assume every Phosphorous atom to be singly ionized. Si has a molar mass of 0.028 kg/mole and density of 2300 kg/m

^{3}/5 M

4(c) If a gas contains 1.2×10

^{27}atoms/m^{3}and radius of atom is 0.53Å, then calculate electronic polarizability and dielectric constant. Find the capacitance of a parallel plate capacitor having this gas inside, with plate area 1 cm^{2}and plate separation 0.12 cm.5 M

5(a) Find Miller Indices of a plane whose intercepts are a, 4a and a, where a is the lattice constant. Draw (102), (201] and (040) in a cubic unit cell.

5 M

5(b) In a semiconductor with Hall co-efficient 145cc/C having width of 2 cm and thickness 0.2 cm with a magnetic field induction of 2T along the smaller dimensions, a current of 150mA is passing. Calculate the current density and Hall voltage.

5 M

5(c) Write Sabine’s formula explaining each term. Explain how this formula can be used for the determination of absorption co-efficient of a given material.

5 M

6(a) Write five distinct differences between Frenkel and Schottky defect.

5 M

6(b) Explain how a voltage difference is generated in a p- junction when it is used in a photovoltaic solar cell.

5 M

6(c) Explain the principle, construction and working of a magnetostriction oscillator to produce ultrasonic waves.

5 M

## MAY 2014

ove any five from the following :-

1 (a) What is x-rays? Why the x-ray are prefered to study crystaline solid.

3 M

1 (b) Represent the following in the cubic unit cell (021), (123), [121]

3 M

1 (c) Find the miller indices of a set of parallel panes which makes intercepts in the ratio 3a:4b on the x and y axes and parallel ti Z-axis

3 M

1 (d) What is Fermi level and Fermi energy? Write Fermi-Dirac distribution function.

3 M

1 (e) Explain the concept of hole in a semiconductor

3 M

1 (f) Draw the structure of quartz crystal and explain its various axes.

3 M

1 (g) State and explain ohm’s law in magnetic circuit?

3 M

2 (a) Describe the formation of energy band in solid? Explain how it helps to classify the solid in to conductors, insulator and semiconductor with proper diagram.

8 M

2 (b) Explain Dimond crystal structure with proper diagram and determine its APF?

7 M

3 (a) Derive the Bragg’s law and describe the powder method to determine crystal structure of powdered specimen.

8 M

3 (b) The magnetic field strength of cooper is 10

^{16}ampere / metre. And magnetic susceptibility is -0.8 x 10^{-3}. Calculate magnetic flux density ad magnetisation in cooper.7 M

4 (a) What is liquid crystal state of matter? Draw the diagram to descibe molecular arrangement in their different phases?

5 M

4 (b) Mention different types of polarizability in a dielectric? Explain electorinc polarizability?

5 M

4 (c) Calculate electron and hole concentration in intrinsic silicon at room temperature if its electrical conductivity is 4 x 10

^{-4}mho/m. (mobility of electron = 0.14m^{2}/v-s & mobility of hole =0.040 m^{2}/v-s)5 M

5 (a) Explain with neat diagram construction and working of solar cell.

5 M

5 (b) State the acoustic requirements of good auditorium. Explain how these requirements can be achieved.

5 M

5 (c) If the x-rays of wavelength 1.549 A

^{o}will be reflected from crystal having spacing of 4.255 A^{o}, calculate the smallest glancing angle and highest order of reflection that can be observed.5 M

6 (a) Explain with neat diagram Hysterisis effect in ferromagnetic material.

5 M

6 (b) Explain piezoelectric oscillator to produce USW?

5 M

6 (c) Explain the formation of barries potential in P-N Junction.

5 M

## DEC 2013

Slove any five from the following

1 (a) Define the term space lattice, unit cell and lattice parameter.

3 M

1 (b) Find the interplaner spacing between the family of planes (111) in a crystal of lattice constant 3A?.

3 M

1 (c) Represent the following in the cubic unit cell :-

(IT2), (002), [121]

(IT2), (002), [121]

3 M

1 (d) Define drift current, diffusion current and mobility of charge carriers.

3 M

1 (e) Explain the use of P-N junction as a solar cell.

3 M

1 (f) State with neat diagram direct and inverse Piezoelectric effect.

3 M

1 (g) What is magnetic circuit? Explain Ohm’s Law on case of magnetic circuit.

3 M

2 (a) Explain the hall effect in metal ? Derive the formulae to determine the density and mobility of the electrons.

8 M

2 (b) Define ligancy and critical radius ratio in case of ionic solid. Write the conditions for stability of ionic crystal in 3-D ? Determine critical radius ratio for ligancy 6.

7 M

3 (a) Explain with neat diagram construction of Bragg’s X-ray spectrometer ? Write the procedure to determine crystal structure. Calculate the maximum order of diffraction if X-ray of wave length 0.819 A? is incident on a crystal of lattice spacing 0.282 nm.

8 M

3 (b) Calculate the number of turns required to produce a magnetic flux of 4 x 10

^{5}wb, if iron rod of length 50cm and cross sectional area 4 cm^{2}carrying an electric current 1A is in the form of ring.(Permeability of iron is 65 x 10^{-4}H/m).7 M

4 (a) What is mesomorphic state of matter ? Explain with neat diagram cholesteric phase.

5 M

4 (b) What is dielectric polarization and dielectric susceptibility? Find the relation between them?

5 M

4 (c) The resistivity of intrinsic InSb at room temperature is 2 x 10

^{-4}? cm. if the mobility of electron is 6m^{2}/V-Sec and mobility of hole is 0-2 m^{2}/V-Sec. calculate its instrinsic carrier density.5 M

5 (a) Identify the crystal structure if its density is 9.6 x 10

^{2}kg/m^{3}, lattice constant is 4.3 A? and atomic weight is 23.5 M

5 (b) Explain the formation of depletion region in P-N junction.

5 M

5 (c) Define reverberation time ? State Sabine’s formula and explain the terms involved in it?

5 M

6 (a) What are soft and Hard magnetic materials ? State their properties and applications.

5 M

6 (b) What is Fermi level in semiconductor? Show that in intrinsic semiconductor Fermi level always at the middle between the forbidden energy gap?

5 M

6 (c) An Ultrasonic sound wave is used to detect the position of defect in a steel bar of thickness 50 cm. if the echo times are 40 and 90 ?-sec. Locate the position of defect.

5 M

## MAY 2013

Slove any five from the following

1 (a) Define the term space lattice, unit cell and lattice parameter.

3 M

1 (b) Find the interplaner spacing between the family of planes (111) in a crystal of lattice constant 3A?.

3 M

1 (c) Represent the following in the cubic unit cell :-

(IT2), (002), [121]

(IT2), (002), [121]

3 M

1 (d) Define drift current, diffusion current and mobility of charge carriers.

3 M

1 (e) Explain the use of P-N junction as a solar cell.

3 M

1 (f) State with neat diagram direct and inverse Piezoelectric effect.

3 M

1 (g) What is magnetic circuit? Explain Ohm’s Law on case of magnetic circuit.

3 M

2 (a) Explain the hall effect in metal ? Derive the formulae to determine the density and mobility of the electrons.

8 M

2 (b) Define ligancy and critical radius ratio in case of ionic solid. Write the conditions for stability of ionic crystal in 3-D ? Determine critical radius ratio for ligancy 6.

7 M

3 (a) Explain with neat diagram construction of Bragg’s X-ray spectrometer ? Write the procedure to determine crystal structure. Calculate the maximum order of diffraction if X-ray of wave length 0.819 A? is incident on a crystal of lattice spacing 0.282 nm.

8 M

3 (b) Calculate the number of turns required to produce a magnetic flux of 4 x 10

^{5}wb, if iron rod of length 50cm and cross sectional area 4 cm^{2}carrying an electric current 1A is in the form of ring.(Permeability of iron is 65 x 10^{-4}H/m).7 M

4 (a) What is mesomorphic state of matter ? Explain with neat diagram cholesteric phase.

5 M

4 (b) What is dielectric polarization and dielectric susceptibility? Find the relation between them?

5 M

4 (c) The resistivity of intrinsic InSb at room temperature is 2 x 10

^{-4}? cm. if the mobility of electron is 6m^{2}/V-Sec and mobility of hole is 0-2 m^{2}/V-Sec. calculate its instrinsic carrier density.5 M

5 (a) Identify the crystal structure if its density is 9.6 x 10

^{2}kg/m^{3}, lattice constant is 4.3 A? and atomic weight is 23.5 M

5 (b) Explain the formation of depletion region in P-N junction.

5 M

5 (c) Define reverberation time ? State Sabine’s formula and explain the terms involved in it?

5 M

6 (a) What are soft and Hard magnetic materials ? State their properties and applications.

5 M

6 (b) What is Fermi level in semiconductor? Show that in intrinsic semiconductor Fermi level always at the middle between the forbidden energy gap?

5 M

6 (c) An Ultrasonic sound wave is used to detect the position of defect in a steel bar of thickness 50 cm. if the echo times are 40 and 90 ?-sec. Locate the position of defect.

5 M

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