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Physics

Medium Exam Preparation: 3-4 days
Question Papers (7)
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FM: 60 PM: 24

Physics

2078 Physics

Section A

Answer any two questions.

1

Design electrical conductivity of semiconductors. Derive expression for conductivity in terms of impurity ionization energy. Give a plot to discuss “Theoretical temperature dependence of the electrical conductivity of an impurity semiconductor”.

10

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2

Describe processes involved in the fabrication of integrated circuits include epitaxial growth, oxidation, oxide removal and pattern definition, doping (impurities in the Si), and interconnection of components.

10

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3

Find expression for force on a current-carrying wire in a magnetic field to find the force experienced by a single charge.

10

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Section B

Answer any eight questions.

4

Give spectrum of Hydrogen atom and discuss its lines.

5

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5

Describe a brief account of Kronig-Penny model.

5

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6

Describe the term “space quantization”.

5

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7

A given spring stretches 0.1m when a force of 20N pulls on it. A 2-kg block attached to it on  a frictionless surface is pulled to the right 0.2m and released.

What is the frequency of oscillation of the block?
What are the velocity and acceleration when x = 0.12m, on the block’s first passing this point?

5

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8

A proton is moving with a velocity v = (3 x 105 i + 7 x 105 k) m/sec in a region where there is a magnetic field B = 0.4j T. Find the force experienced by the proton.

5

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9

A neutron spectroscopy a beam of mono energetic neutrons is obtained by reflecting reactor neutrons from a beryllium crystal. If separation between the atomic planes of the beryllium crystal is 0.732 A°, what is the angle between the incident neutron beam and the atomic planes that will yield a monochromatic beam of neutrons of wavelength 0.1 A°.

5

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10

How many atomic states are there in hydrogen with n=3?
How are they distributed among the subshells? Label each state with the appropriates set of quantum numbers n, 1,m,m
Show that the number of states in a shell, that is ,states having the same n. is given by (2n^2).

5

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11

The density of aluminum is 2.70 g/cm3 and its molecular weight is 26.98 g/mole.

Calculate the Fermi energy
If the experimental value of EF is 12 eV, What is the electron effective mass in aluminum? Aluminum is trivalent.

5

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12

Analyze the circuit in the figure below. Determine the logic function performed by the circuit by making and justifying the appropriate truth table

5

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