# Physics - (PH) 2018 GATE Paper (Practice Test)

## 65 Questions MCQ Test GATE Past Year Papers for Practice (All Branches) | Physics - (PH) 2018 GATE Paper (Practice Test)

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Attempt Physics - (PH) 2018 GATE Paper (Practice Test) | 65 questions in 180 minutes | Mock test for GATE preparation | Free important questions MCQ to study GATE Past Year Papers for Practice (All Branches) for GATE Exam | Download free PDF with solutions
QUESTION: 1

Solution:
QUESTION: 2

Solution:
QUESTION: 3

### For and cos �� are both decreasing functions in the interval ________.

Solution:
QUESTION: 4

The area of an equilateral triangle is √3. What is the perimeter of the triangle?

Solution:
QUESTION: 5

Arrange the following three-dimensional objects in the descending order of their volumes:
(i) A cuboid with dimensions 10 cm, 8 cm and 6 cm
(ii) A cube of side 8 cm
(iii) A cylinder with base radius 7 cm and height 7 cm
(iv) A sphere of radius 7 cm

Solution:
QUESTION: 6

An automobile travels from city A to city B and returns to city A by the same route. The speed of the vehicle during the onward and return journeys were constant at 60 km/h and 90 km/h, respectively. What is the average speed in km/h for the entire journey?

Solution:
QUESTION: 7

A set of 4 parallel lines intersect with another set of 5 parallel lines. How many parallelograms are formed?

Solution:
QUESTION: 8

To pass a test, a candidate needs to answer at least 2 out of 3 questions correctly. A total of 6,30,000 candidates appeared for the test. Question A was correctly answered by 3,30,000 candidates. Question B was answered correctly by 2,50,000 candidates. Question C was answered correctly by 2,60,000 candidates. Both questions A and B were answered correctly by 1,00,000 candidates. Both questions B and C were answered correctly by 90,000 candidates. Both questions A and C were answered correctly by 80,000 candidates. If the number of students answering all questions correctly is the same as the number answering none, how many candidates failed to clear the test?

Solution: QUESTION: 9

The value of the integral given below is Solution: ⇒x2(sin x) - 2x(-cos x) + 2(-sin x)
⇒ (∏2 sin ∏ + 2∏cos ∏ - 2sin ∏) – (0 + 0 + 0)
⇒ (∏2 0 + 2∏(-1) - 2 x 0)  =⇒  -2∏

QUESTION: 10

In a detailed study of annual crow births in India, it was found that there was relatively no growth during the period 2002 to 2004 and a sudden spike from 2004 to 2005. In another unrelated study, it was found that the revenue from cracker sales in India which remained fairly flat from 2002 to 2004, saw a sudden spike in 2005 before declining again in 2006. The solid line in the graph below refers to annual sale of crackers and the dashed line refers to the annual crow births in India. Choose the most appropriate inference from the above data. Solution:
QUESTION: 11

The eigenvalues of a Hermitian matrix are all

Solution:
QUESTION: 12

Which one of the following represents the 3p radial wave function of hydrogen atom? (a0 is the Bohr radius)

Solution:
QUESTION: 13

Given the following table, which one of the following correctly matches the experiments from Group I to their inferences in Group II?

Solution:
QUESTION: 14

In spherical polar coordinates (r, ��, ��), the unit vector Solution:
QUESTION: 15

The scale factors corresponding to the covariant metric tensor gij in spherical polar coordinates are

Solution:
QUESTION: 16

In the context of small oscillations, which one of the following does NOT apply to the normal coordinates?

Solution:
QUESTION: 17

For the given unit cells of a two dimensional square lattice, which option lists all the primitive cells? Solution:
QUESTION: 18

Among electric field magnetic field angular momentum and vector potential which is/are odd under parity (space inversion) operation?

Solution:
QUESTION: 19

The expression for the second overtone frequency in the vibrational absorption spectra of a diatomic molecule in terms of the harmonic frequency ωe and anharmonicity constant ex is

Solution:
QUESTION: 20

Match the physical effects and order of magnitude of their energy scales given below, where is fine structure constant; me and mp are electron and proton mass, respectively. Solution:
QUESTION: 21

The logic expression can be simplified to

Solution:
QUESTION: 22

At low temperatures (T), the specific heat of common metals is described by (with α and β as constants)

Solution:
QUESTION: 23

In a 2-to-1 multiplexer as shown below, the output  Which one of the following is the correct implementation of this multiplexer?

Solution:
QUESTION: 24

The elementary particle  E0 is placed in the baryon decuplet, shown below, at Solution:
QUESTION: 25

The intrinsic/permanent electric dipole moment in the ground state of hydrogen atom is (a0 is the Bohr radius)

Solution:
QUESTION: 26

The high temperature magnetic susceptibility of solids having ions with magnetic moments can be described by as absolute temperature and �� as constant.  The three behaviors i.e. paramagnetic, ferromagnetic and anti-ferromagnetic are described, respectively, by

Solution:
QUESTION: 27

Which one of the following is an allowed electric dipole transition?

Solution:
QUESTION: 28

In the decay, Solution:
QUESTION: 29

A spaceship is travelling with a velocity of 0.7c away from a space station. The spaceship ejects a probe with a velocity 0.59c opposite to its own velocity. A person in the space station would see the probe moving at a speed Xc, where the value of X is ________ (up to three decimal places).

Solution:
QUESTION: 30

For an operational amplifier (ideal) circuit shown below, if V1 = 1 V and V2 = 2 V, the value of V0 is ________V (up to one decimal place).

Solution:
QUESTION: 31

An infinitely long straight wire is carrying a steady current I. The ratio of magnetic energy density at distance r1 to that at r2(= 2 r1) from the wire is ________.

Solution:
QUESTION: 32

A light beam of intensity I0 is falling normally on a surface.  The surface absorbs 20% of the intensity and the rest is reflected. The radiation pressure on the surface is given by X I0 ⁄C , where X is ________ (up to one decimal place). Here C is the speed of light.

Solution:
QUESTION: 33

The number of independent components of a general electromagnetic field tensor is ________.

Solution:
QUESTION: 34

What is the value of the effective density of states function in the conduction band at 300k?

Solution: Substituting the values of mn = m0 ,h = 6.626 * 10-34J/s, k =1.38 * 10-23 and T = 300K, we get
Nc = 2.5 * 1019 cm-3.

QUESTION: 35

For nucleus state is at 90 keV.  Assuming to be a rigid rotor, the energy of its 4+ state is ________ keV (up to one decimal place).

Solution:
QUESTION: 36

Given which one of the following makes a complete set for a three dimensional real linear vector space ?

Solution:
QUESTION: 37

An interstellar object has speed �� at the point of its shortest distance R from a star of much larger mass M. Given �� 2 = 2 GM/R, the trajectory of the object is

Solution:
QUESTION: 38

A particle moves in one dimension under a potential V(x) = a|x| with some non-zero total energy. Which one of the following best describes the particle trajectory in the phase space?

Solution:
QUESTION: 39

Consider an infinitely long solenoid with N turns per unit length, radius R and carrying a current where α is a constant and ω is the angular frequency. The magnitude of electric field at the surface of the solenoid is

Solution:
QUESTION: 40

A constant and uniform magnetic field pervades all space. Which one of the following is the correct choice for the vector potential in Coulomb gauge?

Solution:
QUESTION: 41

If m is the Hamiltonian for a free particle with mass m, the commutator [x, [x, H]] is

Solution:
QUESTION: 42

A long straight wire, having radius a and resistance per unit length r, carries a current l. The magnitude and direction of the Poynting vector on the surface of the wire is

Solution:
QUESTION: 43

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

Solution:
QUESTION: 44

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

Solution:
QUESTION: 45

The energy dispersion for electrons in one dimensional lattice with lattice parameter a is given by E(k) = where W and E0 are constants.  The effective mass of the electron near the bottom of the band is

Solution:
QUESTION: 46

Amongst electrical resistivity (ρ), thermal conductivity (k), specific heat (C), Young’s modulus (Y), and magnetic susceptibility (Y), which quantities show a sharp change at the superconducting transition temperature?

Solution:
QUESTION: 47

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 135° with the x-axis as shown. The emergent electromagnetic wave would be

Solution:
QUESTION: 48

A p-doped semiconductor slab carries a current l = 100 mA in a magnetic field B = 0.2 T as shown.  One measures Vy = 0.25 mV and Vx = 2 mV.  The mobility of holes in the semiconductor is ________ m2V–1s–1 (up to two decimal places). Solution:
QUESTION: 49

An n-channel FET having Gate-Source switch-off voltage is used to invert a 0 – 5 V square-wave signal as shown.  The maximum allowed value of R would be ________ kW (up to two decimal places). Solution:
QUESTION: 50

Inside a large nucleus, a nucleon with mass 939 MeVc–2 has Fermi momentum 1.40 fm–1 at absolute zero temperature. Its velocity is Xc, where the value of X is ________ (up to two decimal places). (ℏc = 197 MeV-fm)

Solution:
QUESTION: 51

4 MeV y-rays emitted by the de-excitation of 19F are attributed, assuming spherical symmetry, to the transition of protons from 1d3/2 state to 1d5/2 state.  If the contribution of spin-orbit term to the total energy is written as the magnitude of C is ________ MeV (up to one decimal place).

Solution:
QUESTION: 52

An α particle is emitted by a nucleus. Assuming the potential to be purely Coulombic beyond the point of separation, the height of the Coulomb barrier is ________ MeV (up to two decimal places). Solution:
QUESTION: 53

For the transformation (where α is a constant) to be canonical, the value of α is________.

Solution:
QUESTION: 54

Given and boundary conditions f(0) = 1 and f(1) = 0, the value of f(0.5) is ________ (up to two decimal places).

Solution:
QUESTION: 55

The absolute value of the integral over the circle in complex plane, is ________ (up to two decimal places).

Solution:
QUESTION: 56

A uniform circular disc of mass m and radius R is rotating with angular speed ω about an axis passing through its center and making an angle �� = 30∘ with the axis of the disc. If the kinetic energy of the disc is the value of α is ________ (up to 2 decimal places). Solution:
QUESTION: 57

The ground state energy of a particle of mass m in an infinite potential well is E0. It changes to when there is a small potential bump of height and width a = L/100, as shown in the figure. The value of α is ________ (up to two decimal places). Solution:
QUESTION: 58

An electromagnetic plane wave is propagating with an intensity l = 1.0 × 105 Wm–2 in a medium with . The amplitude of the electric field inside the medium is ________ × 103 Vm–1 (up to one decimal place). Solution:
QUESTION: 59

A microcanonical ensemble consists of 12 atoms with each taking either energy 0 state, or energy state. Both states are non-degenerate. If the total energy of this ensemble is 4, its entropy will be ________ kB (up to one decimal place), where kB is the Boltzmann constant.

Solution:

The number of ways having total energy 4∈, out of 12 atom is 12 x 11 x 10 x 9 / 4 x 3 x 2  = 495
Hence, entropy, S = kB lnw = kB In(495) = kB (6.204) = 6.204kB

QUESTION: 60

A two-state quantum system has energy eigenvalues corresponding to the normalized states . At time t = 0, the system is in quantum state The probability that the system will be in the same state at is ________ (up to two decimal places).

Solution:    Now, probability in the same state QUESTION: 61

An air-conditioner maintains the room temperature at 27 oC while the outside temperature is 47 oC. The heat conducted through the walls of the room from outside to inside due to temperature difference is 7000 W. The minimum work done by the compressor of the airconditioner per unit time is ________ W.

Solution:
QUESTION: 62

Two solid spheres A and B have same emissivity. The radius of A is four times the radius of B, and temperature of A is twice the temperature of B. The ratio of the rate of heat radiated from A to that from B is ________.

Solution:

Radius r1 of sphere A is 4 times the radius r2 of sphere B
Temperature T1 of sphere A is 2 times the temperature T2 of radius of sphere B
Let E1 be heat radiated by sphere A and E2 be heat radiated by sphere B

E1/E2 = R1^2*T1^4/R2^2*T2^4
=>      16R2^16*T2^4 / R2^2*T2^4
=>      16*16
=>       256
E1/E2 = 256
Ratio of heat radiated by sphere A to sphere B is 256.

QUESTION: 63

The partition function of an ensemble at a temperature T is where kB is the Boltzmann constant. The heat capacity of this ensemble at is XNkB , where the value of X is ________ (up to two decimal places).

Solution:

The partition function, The average energy,    QUESTION: 64

An atom in its singlet state is subjected to a magnetic field.  The Zeeman splitting of its 650 nm spectral line is 0.03 nm.  The magnitude of the field is ________ Tesla (up to two decimal places). Solution:
QUESTION: 65

The quantum effects in an ideal gas become important below a certain temperature TQ when de Broglie wavelength corresponding to the root mean square thermal speed becomes equal to the inter-atomic separation. For such a gas of atoms of mass 2 × 10−26 kg and number density (up to one decimal place). Solution: Use Code STAYHOME200 and get INR 200 additional OFF Use Coupon Code