WBCS Mains Physics Modern Physics Questions 2023

Q. What is India’s first nuclear reactor?

(A) RAMBHA
(B) MENAKA
(C) URVASI
(D) APSARA

Correct Answer: (D) APSARA

Q. The principle of controlled chain reaction is used in

(A) Atom bomb
(B) Atomic energy reactor
(C) The core of the Sun
(D) Artificial radioactivity

Correct Answer: (B) Atomic energy reactor

Q. IAEA looks after the safety related to which type of pollution?

(A) Heavy metals
(B) Hydrocarbon
(C) Plastic
(D) Radioactive elements

Correct Answer: (D) Radioactive elements

Q. An N-type semiconductor is

(A) Negatively charged
(B) Positively charged
(C) Neutral
(D) Negatively or positively charged depending upon the amount and substance of impurity

Correct Answer: (C) Neutral

Q. The Fukushima nuclear disaster took place in

(A) 2010
(B) 2011
(C) 2012
(D) 2014

Correct Answer: (B) 2011

Q. Cyclotron is a device which is used for

(A) Measuring the charge
(B) Measuring the voltage
(C) Accelerating electrons
(D) Accelerating protons

Correct Answer: (D) Accelerating protons

Q. Which radioactive metal is responsible for the Chernobyl accident?

(A) Radioactive Uranium
(B) Radioactive Caesium
(C) Radioactive Plutonium
(D) Radioactive Polonium

Correct Answer: (A) Radioactive Uranium

WBCS Mains Physics Modern Physics Questions 2022

Q. Which of the following superconducting materials has the highest critical temperature and highest critical magnetic flux density?

(A) Lead
(B) Nb-Zr alloy
(C) Nb₃Ge
(D) YBa₂Cu₃O₇

Correct Answer: (D) YBa₂Cu₃O₇

Q. The main hindrance of nanomaterials is

(A) Large surface area to volume ratio
(B) Uniform size distribution in nanometer range
(C) Coarsening effect from Ostwald ripening or agglomeration on aging
(D) Even morphology

Correct Answer: (C) Coarsening effect from Ostwald ripening or agglomeration on aging

Q. Zener diode is used as

(A) Coupler
(B) Rectifier
(C) Amplifier
(D) Voltage regulator

Correct Answer: (D) Voltage regulator

Q. C-dating application of radioisotope ¹⁴C emits

(A) Alpha particle
(B) Beta particle
(C) Gamma ray
(D) Positrons

Correct Answer: (B) Beta particle

Q. Which of the following reactions is an example of a nuclear fusion reaction?

(A) ²₁H + ³₁H → ⁴₂He + ¹₀n
(B) ¹²₆C + ¹₁H → ¹³₇N + γ
(C) ²³⁵₉₂U + ¹₀n → ¹⁴²₅₆Ba + ⁹¹₃₆Kr + 3(¹₀n)
(D) ¹⁴₇N + ¹₀n → ¹²₆C + ³₁H

Correct Answer: (A) ²₁H + ³₁H → ⁴₂He + ¹₀n

Q. In an N-type semiconductor, ultrapure Si is doped with

(A) Boron
(B) Aluminum
(C) Phosphorous
(D) Indium

Correct Answer: (C) Phosphorous

Q. The material used as fuel rod in a nuclear reactor is

(A) Graphite
(B) UO₂
(C) D₂O
(D) ZrO₂

Correct Answer: (B) UO₂

Q. A light-emitting diode produces light when

(A) Forward biased
(B) Reverse biased
(C) Unbiased
(D) None of the above

Correct Answer: (A) Forward biased

Q. LED and LASER diodes are made of

(A) Al
(B) Ga
(C) As
(D) GaAs

Correct Answer: (D) GaAs

WBCS Mains Physics Modern Physics Questions 2021

Q. The maximum biological damage is produced by

(A) X-ray
(B) Gamma ray
(C) Beta ray
(D) Alpha ray

Correct Answer: (D) Alpha ray

Q. Electric conduction in a semiconductor occurs due to

(A) Electrons only
(B) Holes only
(C) Neither electrons nor holes
(D) Both electrons and holes

Correct Answer: (D) Both electrons and holes

Q. The Sun obtains its radiant energy from

(A) Fission process
(B) Disintegration process
(C) Photoelectric process
(D) Fusion process

Correct Answer: (D) Fusion process

Q. Which of the following radiations is most detrimental to human beings?

(A) Alpha rays
(B) Beta rays
(C) Gamma rays
(D) X-rays

Correct Answer: (C) Gamma rays

Q. The nuclear reactor performs a similar function as that of ________ in a thermal power plant.

(A) Boiler
(B) Turbine
(C) Electric generator
(D) Furnace

Correct Answer: (A) Boiler

Q. Name the scientist who discovered the ‘Quantum Statistics’.

(A) S. N. Bose
(B) M. N. Saha
(C) J. C. Bose
(D) C. V. Raman

Correct Answer: (A) S. N. Bose

WBCS Mains Physics Modern Physics Questions 2020

Q. Einstein proposed the idea of the Special Theory of Relativity in the year

(A) 1901
(B) 1903
(C) 1905
(D) 1907

Correct Answer: (C) 1905

Q. Einstein received the Nobel Prize for his work on

(A) Special Theory of Relativity
(B) General Theory of Relativity
(C) Brownian Motion
(D) Photoelectric Effect

Correct Answer: (D) Photoelectric Effect

Q. The uncertainty relation in quantum mechanics was proposed by

(A) Rutherford
(B) Bohr
(C) Heisenberg
(D) Feynman

Correct Answer: (C) Heisenberg

Q. What is the typical size of an atom?

(A) 1 metre
(B) 10⁻² metre
(C) 10⁻⁶ metre
(D) 10⁻¹⁰ metre

Correct Answer: (D) 10⁻¹⁰ metre

Q. A nucleus has 6 protons and 8 neutrons. The nucleus emits two alpha particles. How many protons and neutrons will be left in the nucleus?

(A) 2 and 4
(B) 2 and 2
(C) 4 and 6
(D) 5 and 7

Correct Answer: (A) 2 and 4

Q. In one average life of radioactive decay

(A) Half the active nuclei decay.
(B) Less than half the active nuclei decay.
(C) More than half the active nuclei decay.
(D) All the nuclei decay.

Correct Answer: (C) More than half the active nuclei decay.

Q. Electron was discovered by

(A) Bohr
(B) Thomson
(C) Planck
(D) Heisenberg

Correct Answer: (B) Thomson

Q. The age of our universe is closest to

(A) 13.8 years
(B) 13.8 thousand years
(C) 13.8 million years
(D) 13.8 billion years

Correct Answer: (D) 13.8 billion years

Q. Which of the following is a wrong description of the binding energy of a nucleus?

(A) It is the energy required to break a nucleus into its constituent nucleons.
(B) It is the energy made available when free nucleons combine to form a nucleus.
(C) It is the sum of the rest mass energies of its nucleons minus the rest mass energy of the nucleus.
(D) It is the sum of the kinetic energy of all the nucleons in the nucleus.

Correct Answer: (D) It is the sum of the kinetic energy of all the nucleons in the nucleus.

Q. In the Rutherford experiment towards the discovery of the atomic nucleus, the target used was

(A) Gold
(B) Silver
(C) Platinum
(D) Copper

Correct Answer: (A) Gold

Q. Energy generation in stars takes place mainly via

(A) Nuclear fission
(B) Chemical displacement reaction
(C) Nuclear fusion
(D) Chemical additive reaction

Correct Answer: (C) Nuclear fusion

Q. The first Nobel Prize in Physics was awarded for the discovery of

(A) Photoelectric effect
(B) Atomic nucleus
(C) X-ray
(D) Special Theory of Relativity

Correct Answer: (C) X-ray

WBCS Mains Physics Modern Physics Questions 2019

Q. Black holes were predicted by

(A) Copernicus
(B) Einstein
(C) Rutherford
(D) Satyen Bose

Correct Answer: (B) Einstein

Q. In a radioactive decay process, the negatively charged emitted beta particles are

(A) The electrons present inside the nucleus.
(B) The electrons produced as a result of the decay of neutrons inside the nucleus.
(C) The electrons produced as a result of collisions between atoms.
(D) None of the above

Correct Answer: (B) The electrons produced as a result of the decay of neutrons inside the nucleus.

Q. In gamma-ray emission from a nucleus

(A) Only proton number changes.
(B) Only neutron number changes.
(C) There is no change in the proton number and neutron number.
(D) Both the proton number and the neutron number change.

Correct Answer: (C) There is no change in the proton number and neutron number.

Q. Which of the following electromagnetic waves has the smallest wavelength?

(A) Infrared rays
(B) UV rays
(C) X-rays
(D) Gamma rays

Correct Answer: (D) Gamma rays

Q. The function of heavy water in a nuclear reactor is to

(A) Cool down the reactor.
(B) Stop the nuclear reaction.
(C) Slow down the speed of neutrons.
(D) Increase the speed of neutrons.

Correct Answer: (C) Slow down the speed of neutrons.

Q. For radioactive nuclei that undergo either alpha or beta decay, which one of the following cannot occur?

(A) An isobar of the original nucleus is produced.
(B) An isotope of the original nucleus is produced.
(C) A nucleus with a higher atomic number than that of the original nucleus is produced.
(D) A nucleus with a lower atomic number than that of the original nucleus is produced.

Correct Answer: (B) An isotope of the original nucleus is produced.

Q. If the band gap between the valence band and conduction band in a material is 5.0 eV, then the material is

(A) Semiconductor
(B) Good conductor
(C) Superconductor
(D) Insulator

Correct Answer: (D) Insulator

Q. During the emission of a positron from a nucleus, the mass number of the daughter element remains the same but the atomic number

(A) Is decreased by 1 unit
(B) Is decreased by 2 units
(C) Is increased by 1 unit
(D) Remains unchanged

Correct Answer: (A) Is decreased by 1 unit

Q. The emission spectrum of hydrogen discovered first and the region of the electromagnetic spectrum in which it belongs, respectively are

(A) Lyman, ultraviolet
(B) Lyman, visible
(C) Balmer, ultraviolet
(D) Balmer, visible

Correct Answer: (D) Balmer, visible

Q. What is the main energy generation process in the Sun?

(A) Nuclear fission
(B) Nuclear radioactive decay
(C) Gravitational energy
(D) Nuclear fusion

Correct Answer: (D) Nuclear fusion

Q. Formation of stars begins primarily from the following two gases

(A) Hydrogen and Nitrogen
(B) Nitrogen and Oxygen
(C) Oxygen and Hydrogen
(D) Hydrogen and Helium

Correct Answer: (D) Hydrogen and Helium

WBCS Mains Physics Modern Physics Questions 2018

Q. For deriving a p-type semiconductor, the element to be mixed with silicon is

(A) Phosphorus
(B) Aluminium
(C) Arsenic
(D) None of the above

Correct Answer: (B) Aluminium

Q. The connecting material in solar panels is

(A) Silicon (Si)
(B) Silver
(C) Selenium
(D) Copper (Cu)

Correct Answer: (B) Silver

Q. Nucleons are the number of

(A) Protons present in the nucleus.
(B) Neutrons present in the nucleus.
(C) Sum of protons and neutrons in the nucleus.
(D) Total protons, neutrons and electrons in the atom.

Correct Answer: (C) Sum of protons and neutrons in the nucleus.

Q. The spin of a Boson particle is equal to

(A) Positive integer
(B) Negative integer
(C) Positive integral multiple of 1/2
(D) Any fraction

Correct Answer: (A) Positive integer

Q. The water used in a nuclear reactor is called

(A) Hard water
(B) Heavy water
(C) Nuclear water
(D) Critical water

Correct Answer: (B) Heavy water

Q. The electrical resistivity of a semiconductor

(A) Increases with temperature
(B) Decreases with temperature
(C) Does not change with temperature
(D) Decreases at lower temperature but decreases at higher temperature

Correct Answer: (B) Decreases with temperature

WBCS Mains Physics Modern Physics Questions 2017

Q. Atomic packing density in an FCC lattice is

(A) 0.47
(B) 0.68
(C) 0.74
(D) 1.0

Correct Answer: (C) 0.74

Q. An intrinsic semiconductor has a forbidden gap of

(A) 2 eV
(B) > 2 eV
(C) < 2 eV
(D) None of the above

Correct Answer: (C) < 2 eV

Q. The specific gravity of beta-quartz is

(A) 2.32 g/cc
(B) 2.63 g/cc
(C) 2.53 g/cc
(D) 2.2 g/cc

Correct Answer: (B) 2.63 g/cc

Q. A transistor is made of

(A) Doped semiconductors
(B) Intrinsic semiconductors
(C) A metal piece sandwiched between two intrinsic semiconductors
(D) None of the above

Correct Answer: (A) Doped semiconductors

Q. The isotope used as fuel in a nuclear power plant is

(A) U-235
(B) U-238
(C) U-233
(D) U-239

Correct Answer: (A) U-235

Q. A carbon microphone is best used in

(A) Dynamo
(B) Telephone
(C) Transformer
(D) None of the above

Correct Answer: (B) Telephone

WBCS Mains Physics Modern Physics Questions 2016

Q. Confirmation of the presence of Higgs Boson will justify

(A) Both the Standard Model and Superstring Theory.
(B) The unification of all the four fundamental forces.
(C) The Steady State Model of the Universe.
(D) The mass of the fundamental particles.

Correct Answer: (D) The mass of the fundamental particles.

Q. What is viewed through an electron microscope?

(A) Electrons and other elementary particles
(B) Structure of bacteria and viruses
(C) Inside of the human stomach
(D) Inside of the human eye

Correct Answer: (B) Structure of bacteria and viruses

Q. In a nuclear reaction, there is conservation of

(A) Energy only
(B) Momentum only
(C) Mass, energy and momentum
(D) Mass only

Correct Answer: (C) Mass, energy and momentum

Q. Particles which can be added to the nucleus of an atom without changing its chemical properties are

(A) Electrons
(B) Protons
(C) Neutrons
(D) Alpha-particles

Correct Answer: (C) Neutrons

Q. The mass-energy relation is the outcome of

(A) Quantum Theory
(B) General Theory of Relativity
(C) Field Theory of Relativity
(D) Special Theory of Relativity

Correct Answer: (D) Special Theory of Relativity

Q. Which of the following television displays works on the principle of semiconductor?

(A) Plasma Display
(B) Liquid Crystal Display
(C) Light Emitting Diode Display
(D) None of the above

Correct Answer: (C) Light Emitting Diode Display

Q. LEC or Light Emitting Electrochemical Cell is a different mode of operation of

(A) LEDs
(B) CRTs
(C) LCDs
(D) OLEDs

Correct Answer: (D) OLEDs

Q. Which of the following persons discovered gamma rays?

(A) Paul Villard
(B) Marie Curie
(C) J. J. Thomson
(D) Adam Osborne

Correct Answer: (A) Paul Villard

Q. Which one of the following displays is non-volatile?

(A) Plasma
(B) Liquid Crystal Display
(C) Organic Light Emitting Diode
(D) Cholesteric Display

Correct Answer: (D) Cholesteric Display

Q. Which of the following is an example of an ideal black body?

(A) Blackboard
(B) Kajol
(C) A pinhole box
(D) None of the above

Correct Answer: (C) A pinhole box

Q. A radioactive decay process has a half-life of 4 years. The amount of the reactant remaining after 12 years is

(A) 10%
(B) 12.5%
(C) 25%
(D) 87.5%

Correct Answer: (B) 12.5%

Q. Radioactive substance used in dating geological objects is

(A) C-12
(B) C-11
(C) C-14
(D) None of the above

Correct Answer: (C) C-14

Q. Which one of the following is not radioactive?

(A) Astatine
(B) Francium
(C) Tritium
(D) Zirconium

Correct Answer: (D) Zirconium

Q. The patient is asked to drink barium sulphate (BaSO₄) for examining the stomach by X-rays because X-rays are

(A) Less absorbed by heavy atoms.
(B) More absorbed by heavy atoms.
(C) Reflected by heavy atoms.
(D) Refracted by heavy atoms.

Correct Answer: (B) More absorbed by heavy atoms.

Q. Who first demonstrated experimentally the existence of electromagnetic waves?

(A) Hertz
(B) Rømer
(C) Marconi
(D) Maxwell

Correct Answer: (A) Hertz

WBCS Mains Physics Modern Physics Questions 2015

Q. In a nuclear reactor, the chain reaction is controlled by introducing

(A) Iron rods
(B) Cadmium rods
(C) Graphite rods
(D) Platinum rods

Correct Answer: (B) Cadmium rods

Q. Photoelectric emission occurs only when the incident light has more than a certain minimum

(A) Power
(B) Wavelength
(C) Intensity
(D) Frequency

Correct Answer: (D) Frequency

Q. A ‘black hole’ is a body in space which does not allow any radiation to come out. This property is due to its

(A) Very small size
(B) Very large size
(C) Very high density
(D) Very low size

Correct Answer: (C) Very high density

Q. Which one of the following laser types is used in a laser printer?

(A) Dye laser
(B) Gas laser
(C) Semiconductor laser
(D) Excimer laser

Correct Answer: (C) Semiconductor laser

Q. Encoder is a

(A) Integrated circuit
(B) Digital circuit
(C) VLSI
(D) IC chips

Correct Answer: (B) Digital circuit

Q. Which of the following is a good nuclear fuel?

(A) Uranium-238
(B) Neptunium-239
(C) Plutonium-239
(D) Thorium-236

Correct Answer: (C) Plutonium-239

WBCS Mains Physics Modern Physics Questions 2014

Q. The reaction that takes place inside the Sun to power it is

(A) Fission
(B) Fusion
(C) Oxidation
(D) Decay

Correct Answer: (B) Fusion

Q. The technique of barium X-ray utilizes the following property of barium sulphate

(A) It is opaque to X-rays
(B) It is radioactive
(C) It is transparent to X-rays
(D) It is easily absorbed by tissues

Correct Answer: (A) It is opaque to X-rays

Q. The technique of MRI uses the phenomenon of

(A) Nuclear Magnetic Resonance
(B) Electron Cyclotron Resonance
(C) Optical Resonance
(D) Microwave Resonance

Correct Answer: (A) Nuclear Magnetic Resonance

Q. The half-life period of an isotope is 2 hours. After 6 hours, the fraction of the initial quantity of the isotope left behind will be

(A) 1/6
(B) 1/8
(C) 1/12
(D) 1/16

Correct Answer: (B) 1/8

Q. Albert Einstein was awarded the Nobel Prize for his work on

(A) General Theory of Relativity
(B) Special Theory of Relativity
(C) Quantum Physics
(D) Theory of Photoelectricity

Correct Answer: (D) Theory of Photoelectricity

Q. Stephen Hawking is famous for his contributions to

(A) Nuclear Physics
(B) Quantum Theory
(C) String Theory
(D) Astrophysics

Correct Answer: (D) Astrophysics

Q. Which of the following uranium isotopes is mostly used in nuclear reactors and nuclear weapons?

(A) Uranium-232
(B) Uranium-234
(C) Uranium-235
(D) Uranium-238

Correct Answer: (C) Uranium-235

Q. MRI stands for

(A) Magnetic Resonance Imaging
(B) Magnetic Reflection Imaging
(C) Machine Readable Imaging
(D) Mechanical Reading Instrument

Correct Answer: (A) Magnetic Resonance Imaging