| Post Name | SCIENTIFIC OFFICER(PHYSICS) - KERALA POLICE SERVICE (FSL) |
|---|---|
| Question Paper Code | 019/2021 |
| Category Code | 026/2020 |
| Date of Test | 27 January 2021 |
| Medium of Question | ENGLISH |
| Exam Type | OMR Examination |
| Total Questions | 100 |
1
Consider the following statement regarding a projectile:
(1) The acceleration is not zero anywhere along its trajectory.
(2) Its velocity at the highest point is zero.
(3) The horizontal and vertical components of its motion are completely independent
of each other.
Which among the above statements are true ?
Answer
B. Only (1) & (3)
2
Two objects have equal kinetic energies. How do the magnitudes of their momenta p₁ and p₂ compare?
Answer
D. Insufficient information
3
If the position coordinates of a particle moving in a plane are given by r⃗ = r(cos ωt î + sin ωt ĵ), then the velocity of the particle is given by:
Answer
B. v⃗ = rω(−sin ωt î + cos ωt ĵ)
4
Which among the following is NOT TRUE about fictitious forces ?
Answer
D. Fictitious forces originate due to interaction between bodies.
5
Which among the following is NOT a velocity-dependent force ?
Answer
A. Gravitational force
6
There exists a closed curve C to which nearby trajectories can either spiral in or they can
spiral away from C. Then C is
Answer
B. a limit cycle.
7
Which among the following is an example of unconstrained motion ?
Answer
A. Two particles moving solely under their mutual gravitational attraction.
8
The Lagrangian of a system is given by L = 1/2 Mẋ² + 1/2 m(ẋ² + ẏ² + 2ẋẏ cos α) + mgy sin α. Which among the following represent the components of momenta of the system?
Answer
C. p_x = Mẋ + m(ẋ + ẏ cos α)
9
Which among the following helps in converting the Lagrangian equations into a
Hamiltonian ?
Answer
B. Legendre transform
10
Which among the following correctly represent the Hamiltonian of a simple pendulum ?
pθ2 p θ2
Answer
C. H = mgl cos θ
11
Which among the following is expressed by saying that the Hamiltonian phase flow
preserves volume ?
Answer
D. Liouville’s theorem
12
If is the angular velocity of a particle of mass m that moves with velocity v in a non-
inertial frame, the magnitude of the Coriolis force acting on the body is given by
Answer
B. 2 m v
13
The eigen values of the matrix , are :
3 2
Answer
C. –1, 5
14
Which among the following is NOT a correct representation of complex functions?
Answer
D. sinh(z) = (eᶻ − e⁻ᶻ)/(2i)
15
Which among the following equations relate the Cartesian to the cylindrical unit vectors ?
Answer
A. r̂ = cosî + sin ĵ ; = – sinî + cos ĵ ; ẑ = ẑ
16
The value of (1 + i)8 is given by
Answer
C. 16
17
The recurrence relation (2n + 1)xP_n(x) = (n + 1)P_{n+1}(x) + nP_{n−1}(x) corresponds to
Answer
B. Legendre polynomials
18
Bessel functions of the second kind is also known as:
Answer
D. Neumann function
19
Four coins are tossed simultaneously. What is the probability that none of them are heads ?
Answer
A. 1/16
20
Which among the following is likely to be the Fourier transform of the function f(x) = Ne⁻ᵅˣ²?
Answer
B. N/√(2α) · e^(−ω²/(4α))
21
Which among the following is a current-controlled negative resistance device ?
Answer
B. A uni-junction transistor
22
What is the state of a JFET defined by V_GS = 0 V and V_DS > |V_P|?
Answer
A. ID becomes maximum.
23
Which among the following materials is used to make a light dependent resistor ?
Answer
D. Cadmium Sulphide
24
Which is the most commonly used material to make IR LEDs ?
Answer
A. Gallium Arsenide
25
Which among the following materials is the least preferred in making a p-n junction solar
cell ?
Answer
C. Lead Sulphide
26
Which statement is NOT true about the common-mode rejection ratio (CMRR) of an op-amp?
Answer
D. The larger the value of CMRR, the lower the chance that a common-mode signal is rejected.
27
What will be the output voltage of the given circuit ?
Answer
A. 1 V
28
Identify the following circuit :
Answer
B. First order high pass filter
29
The noise produced by the random motion of charge carriers is
Answer
C. Johnson noise
30
Which is the modulation system in which there are pulses of constant amplitude and
length but with varying timing ?
Answer
A. Pulse Position Modulation
31
Sky waves are refracted back to the Earth from
Answer
B. the ionosphere
32
A free electron has a kinetic energy of 100 eV. Its de Broglie wavelength will be
Answer
C. 0.1226 nm
33
Which among the following is NOT true about the Hilbert space ?
Answer
D. H is inseparable.
2i
34
The bra matrix of the ket | = 3 i is
4
Answer
B. (2i 3 –i – 4)
35
If  is an operator satisfying the eigen value equation
 | = | , then which among the following equations is TRUE about its inverse ?
Answer
D. Â –1 | = –1 |
36
Identify the ODD one from the following matrices:
Answer
C. [[0, −i], [1, 0]]
37
The potential expressed as V(r) = V₀e^(−r/R)/r is known as
Answer
B. Yukawa potential
38
Which among the following Hamiltonians stands for the simple harmonic oscillator ?
1
Answer
A. Ĥ = ħ â†â + 2
39
The dispersion relation for a type of waves is @” = ak + bk?. The wave number k, for
which the phase velocity equals the group velocity is
a a
A —
Answer
A. ne
40
The radius of the second Bohr orbit of a singly ionised helium atom is
Answer
B. 1.06 Å
41
An electric cooker that has 1000 W rating is switched on for ten minutes. How much heat
does it produce ?
Answer
A. 600 kJ
42
If a measurement x takes values 1, 2, 3 and 4 with probabilities in each case, the values
4
of x will be
1
Answer
C. =
43
A microcanonical ensemble has Ω macro states, each with probability Pᵢ = 1/Ω. The entropy of the system is:
Answer
B. k_B ln Ω
44
If a quantum system is in one of a number of states |i with probability Pi, then the
entity defined by = Pi | i i| is called
i
Answer
D. Density matrix.
45
The excess pressure p inside a spherical liquid droplet of radius r and surface tension γ is:
Answer
C. p = 2γ/r
46
A system can occupy energy level −δ/2 or δ/2. Then the partition function of the system is:
Answer
B. Z = 2 cosh(βδ/2)
47
The Gibbs function per particle of a thermodynamic system is called as
Answer
D. Chemical potential
48
Which among the following proportionality is true about Einstein’s A and B co-efficients
and the frequency ?
A A
Answer
C. 3
49
At high temperatures, the molar heat capacity of a Debye solid saturates to a value of
3
Answer
A. 3R
50
The occupancy of the states for fermions is given by:
Answer
B. n̄ = 1/[e^((ε − μ)/kT) + 1]
51
The abrupt accumulation of atoms in the ground state at temperatures below Tc is called
Answer
D. Bose-Einstein condensation
52
A white dwarf star is
Answer
C. a degenerate Fermi gas.
53
Which among the following is NOT true about atomic nuclei ?
Answer
D. The isotopes of an element have the same A value but different N and Z
values.
A 9 019/2021
54
Which among the following numerical quantity corresponds to the magnitude of nuclear
density ?
Answer
C. 1017 kg/m3
55
The magnetic resonance imaging (MRI) works exceptionally well for viewing internal
tissues in human body. Which among the following is the most likely reason for this ?
Answer
A. About two-thirds of the atoms in the human body are hydrogen.
56
Identify the missing particle in the nuclear decay
A A
Z X Z 1 Y ? v
Answer
Question Cancelled
57
Which is the stable end product of the Neptunium radioactive series ?
206 207
Answer
D. 83 Bi
58
Which among the following force carrying particles are exchanged in strong nuclear interaction?
Answer
B. Gluons
59
Which is the practical application of pair annihilation process in medical diagnostics ?
Answer
C. Positron emission tomography
60
Identify the reaction that does not conserve strangeness:
Answer
B. – + p K0 + n
61
Which of the following is the quark structure of the – particle ?
Answer
D. sss
62
The ratio of thermal to electrical conductivity (K/) for any metal is proportional to its
temperature T. This is statement is known as
Answer
C. Wiedemann-Franz law
63
Identify the indirect band gap material :
Answer
A. Crystalline Silicon
64
Identify the lattice represented by the primitive vectors
a
a1 = a x̂ , a2 = aŷ, a3 = ( x̂ + ŷ + ẑ)
2
Answer
B. Body-centred cubic
65
What is the packing fraction of a simple cubic lattice ?
Answer
D. 0.52
66
Identify the crystal that has ionic bonding
Answer
C. Sodium Chloride
67
The dispersion relation for an electron is given by E(k) = ℏ²k²/(2m). Its effective mass is given by
Answer
A. m
68
The density of states for a bulk three-dimensional semiconducting crystal is given by:
Answer
B. g(E) ∝ E¹ᐟ²
69
Identify the Type -1 superconductor among the following :
Answer
D. Aluminium
70
When a superconducting sample is placed in a magnetic field, super currents are
generated to screen the fields from penetrating into the bulk of the sample. This
phenomenon is called
Answer
C. Meissner effect
71
What is the probability that the electron in the ground state of hydrogen will be found
outside the first Bohr radius ?
Answer
C. 67.7%
72
Which among the following transitions is responsible for one of the lines in the sodium
doublet in a sodium vapour lamp ?
Answer
D. 3P1/2 3S1/2
73
Identify the correct equation for allowed values of the rotational energy of a diatomic molecule:
Answer
A. E = [ℏ²/(2I)] J(J + 1)
74
A particle of rest mass m0 is moving uniformly along a straight line with relativistic
velocity kc, where c is the velocity of light in vacuum and 0 < k < 1. The phase velocity
of de Broglie waves associated with the particle is
c c
Answer
B. k k
75
A photon of wavelength is incident on a free electron at rest and is scattered in the
backward direction. The fractional shift in its wavelength in terms of the Compton
wavelength C of the electron is
C 3 C
Answer
D. 3
76
The activity of a radioactive sample is decreased to one-third of the initial value in 100
days. The half-life of the sample is approximately
Answer
B. 63 days
77
Two spherical nuclei with radii R1 and R2 have mass numbers 216 and 27 respectively.
R
Then 1 is given by
R2
Answer
D. 2
78
A microcontroller is an example of
Answer
A. VLSI
79
The control unit of a microprocessor
Answer
Question Cancelled
80
Where does the code used by a microprocessor when it is first switched on is stored ?
Answer
C. ROM
81
The reduced form of the Boolean expression A . B.
Answer
B.
82
The output of a 3-input NAND gate is low when
Answer
D. All inputs are high.
83
What is the width of the address bus in 8085 ?
Answer
C. 16 - bit
84
What is the type of interrupt in 8085 where the interrupt address is known to the
processor ?
Answer
A. Vector interrupt
85
How many comparators are required in a flash ADC with 8 - bit output ?
Answer
D. 255
86
What is the capacity of the onboard RAM of the microcontroller 8051 ?
Answer
C. 128 bytes
87
Which among the following laser has a quasi-three-level system ?
Answer
Question Cancelled
88
Which line broadening is due to the fact that atomic resonance frequencies are distributed
over a band of frequencies ?
Answer
C. Inhomogeneous broadening
89
Which laser uses chemical pumping to achieve population inversion ?
Answer
B. All Gas-Phase Iodine Laser
90
Identify the second order nonlinear optical phenomena related to the quadratic
susceptibility (2).
Answer
D. Sum-frequency generation.
A 13 019/2021
91
The total number of guided modes in a step index fibre is NOT related to
Answer
B. length of the fibre.
92
The mean optical power launched into an 8 km long of fibre that has no connectors or
splices is 100 W. If the mean optical power at the fibre output is 10 W, the overall
signal attenuation in decibels is
Answer
A. 10 dB
93
Consider a beam of light of wavelength incident normally on a system of a polariser
and an analyser. The analyser is oriented at 45° to the polariser. When an optical
component is introduced between them, the output intensity becomes zero. The optical
component is
Answer
C. a half-wave plate.
94
Light travelling between two points in a medium takes a path for which
Answer
B. time of flight is extremum.
95
The wavelength of a photon that has an energy of 3.6 eV is
Answer
D. 345 nm
96
The chemical potential of an ideal Bose gas at any temperature will be
Answer
A. either zero or negative
97
Which among the following crystal structure has a wrong coordination number given ?
Answer
A. face centred cubic - 6
98
A plane cubic lattice intercepts the three crystallographic axes at a , , ,
2 3
respectively. The Miller indices of the plane are
Answer
B. (2 4 3)
99
The exciting radiation in a Raman scattering experiment is 5460 Å and the Stokes line is
at 5520Å. The wavelength of the anti-Stokes line is at
Answer
C. 5400 Å
100
The electromagnetic wave passing though a medium has an electric field E⃗ = E₀ cos(10⁷x + 10⁷y − 10¹⁵t) ẑ. The refractive index of the medium is:
Answer
D. 4.2
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