Questions 561–570 of 650. Imported answers require independent review unless marked reviewed.

Topic practice 650 questionsPage 57 of 65

Question 31

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If

is the Hamiltonian for a free particle with mass

, the commutator

is
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Question 32

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A long straight wire, having radius

and resistance per unit length

, carries a current

. The magnitude and direction of the Poynting vector on the surface of the wire is
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Question 33

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Three particles are to be distributed in four non-degenerate energy levels. The possible number of ways of distribution: (i) for distinguishable particles, and (ii) for identical Bosons, respectively, is
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Question 34

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The term symbol for the electronic ground state of oxygen atom is
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Question 35

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The energy dispersion for electrons in one dimensional lattice with lattice parameter

is given by

, where

and

are constants. The effective mass of the electron near the bottom of the band is
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Question 36

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Amongst electrical resistivity (

), thermal conductivity (

), specific heat (

), Young’s modulus (Y), and magnetic susceptibility (

), which quantities show a sharp change at the superconducting transition temperature?
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Question 37

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A quarter wave plate introduces a path difference of

between the two components of polarization parallel and perpendicular to the optic axis. An electromagnetic wave with

is incident normally on a quarter wave plate which has its optic axis making an angle

with the

-axis as shown. The emergent electromagnetic wave would be
Diagram for Physics question 37

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Question 38

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A p-doped semiconductor slab carries a current

mA in a magnetic field

T as shown. One measures

mV and

mV. The mobility of holes in the semiconductor is ________ m

V

s

(up to two decimal places).
Diagram for Physics question 38


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Question 39

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An n-channel FET having Gate-Source switch-off voltage

is used to invert a 0–5 V square-wave signal as shown.
Diagram for Physics question 39

The maximum allowed value of R would be ______ kΩ (up to two decimal places).

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Question 40

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Inside a large nucleus, a nucleon with mass 939 MeV c

has Fermi momentum 1.40 fm

at absolute zero temperature. Its velocity is Xc, where the value of X is ______ (up to two decimal places).
(

)

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