September 26, 2022

Physics – Science – WBCS Main Question Paper

By Sutirtha Datta WBCS Mains Question Paper 0 Comments

Contents

Physic - Science - WBCS Main Question Paper

physical science question and answer

WBCS Main Question Paper – 2021

2. Pascal is a unit of

(A) Air pressure

(B) Density

(D) Distance

8. An electric motor

(A) generates mechanical energy.

(B) generates electric energy.

(D) converts electrical energy into mechanical energy.

10. Velocity of wind is measured by

(A) Speedometer

(B) Tachometer

(D) Hygrometer

12. Which of the following radiation is most detrimental to human being?

(A) α-rays

(B) B-rays

(D) X-rays

33. A refrigerator is

(A) a heat engine.

(B) an air-cooler.

(D) a heat engine working in reverse order.

41. Sound travels fastest in

(A) Air

(B) Water

(D) Steel

51. A thin oil film on a water surface appears coloured because of

(A) reflection

(B) refraction

(D) polarization

57. The unit of energy in MKS system is

(A) Volt

(B) Erg

(D) Joule

89. Among the following the weakest forces are

(A) Gravitational forces

(B) Electric forces

(D) Nuclear forces

90. Lubricant cannot reduce

(A) Static friction

(B) Kinetic friction

(D) Inertia

159. The surface tension of liquid

(A) increases with area.

(B) decreases with area.

(D) decreases with temperature.

165. The splitting of white light into its components is due to

(A) reflection

(B) refraction

(D) dispersion

175. Electric conduction in a semiconductor occurs due to

(A) Electrons only

(B) Holes only

(D) Both Electrons and Holes

179. Supersonic planes fly

(1,236 km/h at sea level)

(A) with a speed less than the speed of sound.

(B) with the speed of sound.

(D) with the speed of light.

WBCS Main Question Paper – 2020

A piece of wire of resistance R is cut into three equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R, then the ratio ^R/_R, is

(A) ¹/₃

(B) 1

(D) 9

Which of the following frequencies is not in the audible range of sound for human beings ?

(A) 5 Hz

(B) 50 Hz

(D) 5000 Hz

Consider the following statements :

(i) An emf can be induced by moving a conductor in a magnetic field.

(ii) An emf can be induced by changing the magnetic field.

(electromotive force (E) = work done (W) / charge (Q)

(A) (i) is true but (ii) is false

(B) (ii) is true but (i) is false

(D) Both (i) and (ii) are true

Gravitational force on the surface of the moon is

(1.62 m/s², 16.6% of Earth’s)

(A) ¹/₆ of that on the surface of the earth.

(B) ¹/₅ of that on the surface of the earth.

(D) ¹/₃ of that on the surface of the earth.

Which of the following pairs represent units of the same physical quantity ?

(A) Kelvin and Joule

(B) Kelvin and Calorie

(D) Joule and Calorie

In summer, a mild wind is often found on the shore of a calm river. This is caused due to

(A) difference in thermal conductivity of water and soil.

(B) convection currents.

(D) radiation from the soil.

The reading in centigrade scale is (-)40°. What is the corresponding reading on the Fahrenheit scale?

(A) (-)16°

(B) (-) 40°

(D) 40°

A porter lifts a luggage of 15 kg from the ground and puts it on his head 1.5 m above the ground. The work done by him on the luggage is (given g = 10ms^-2)

(W = mgh = 15×10×1.5)

(A) 25 Joule

(B) 125 Joule

(C) 225 Joule

(D) 112.5 Joule

Which of the following elements is a semiconductor ?

(A) Aluminium

(B) Mercury

(C) Silicon

(D) Silver

In terms of basic units of mass(M), length(L) and time (T), dimension of energy is

(A) ML2T^-1

(B) MLT

(D) ML2T^-2

Einstein received Nobel Prize for his work on

(1921, Physics)

(A) special theory of relativity

(B) general theory of relativity

(D) photo electric effect

The quanta of light are called

(A) proton

(B) photon

(D) neutron

When light is refracted, which of the following does not change ?

(A) Frequency

(B) Wavelength

(D) Amplitude

Einstein proposed the idea of special theory of relativity in the year

(A) 1901

(B) 1903

(D) 1907

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

(1901, Wilhelm Röntgen, Germany)

(A) Photoelectric effect

(B) Atomic nucleus

(C) X-ray

(D) Special theory of relativity

Same mass of iron, copper, water and glycerine are heated to 80° centigrade. Which substance among these, will take largest time to cool down to 20° ?

(specific heat)

(A) Iron

(B) Copper

(C) Water

(D) Glycerine

A person clapped his hands near a cliff and heard the echo after 2s. What is the distance of the cliff from the person if the speed of the sound is taken as 346 meter/s ?

(d = ^{V x t}/₂)

(A) 173 meter

(B) 346 meter

(D) 1384 meter

An athlete completes one round of a circular track of diameter 200m. What will be the distance covered (closest value among the options) ?

(2π x ^d/₂)

(A) 528 meter

(B) 628 meter

(D) 1256 meter

A metal sheet with a circular hole is heated. The hole

(A) gets larger

(B) gets smaller

(D) gets deformed

Uncertainty relation in quantum mechanics was proposed by

(1927)

(A) Rutherford

(B) Bohr

(C) Heisenberg

(D) Feynman

The stars twinkle because of

(A) reflection

(B) refraction

(D) interference

Acceleration due to gravity of the earth is maximum at

(g = 9.806 ms^-2)

(A) the center of the earth.

(B) the midpoint of the center and the surface of the earth.

(C) the surface of the earth.

(D) a height equal to the radius of the earth from the surface of the earth.

Two bullets are fired simultaneously and horizontally from the same vertical height. The first bullet has mass and velocity m1 and v1 respectively and the second one has mass and velocity m2 and v2 respectively. Which bullet will hit the ground first ?

(A) The faster one

(B) The slower one

(C) Both will reach simultaneously

(D) Will depend on masses

At the time of a short circuit, the current in the circuit

(A) reduces substantially

(B) does not change

(C) increases heavily

(D) vary continuously

Two resistors R and 2R are connected in series in an electric circuit. The thermal energy developed in R and 2R are in the ratio

(A) 2 : 1

(B) 4 : 1

(D) 1 : 2

The unit of density in CGS system is

(A) gm/cm⁴

(B) gm/cm³

(D) gm/cm

10 miles is equivalent to ________ .

(A) 12 km

(B) 18 km

(D) 16 km

127. 10°C is equivalent to _____.

(°F = °C × 9/5 + 32)

(A) 55°F

(B) 60°F

(D) 52°F

WBCS Main Question Paper – 2019

31. Black holes were predicted by

(A) Copernicus

(B) Einstein

(D) Satyen Bose

114. Which of the following electromagnetic waves have the smallest wavelength?

(A) Infrared rays

(B) UV rays

(D) y-rays

128. Which of these are used to measure optical activity?

(A) Polarimeter

(B) Planometer

(D) Photometer

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

(1885)

(A) Lyman, ultraviolet

(B) Lyman, visible

(D) Balmer, visible

136. A bullet on penetrating 30 cm into its target loses it’s velocity by 50%.What additional distance will it penetrate into the target before it comes to rest?

(A) 30 cm

(B) 20 cm

(D) 5 cm

137. In which of the following phenomena, the heat waves travel along straight lines with the speed of light?

(A) Thermal conduction

(B) Forced convection

(D) Thermal radiation

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

(A) semiconductor

(B) good conductor

(D) insulator

142. In which of the following pairs, the two physical quantities have different dimensions?

(A) Planck’s constant and angular momentum

(B) Impulse and linear momentum

(D) Energy and torque

143. Water is flowing through a very narrow tube. The velocity of water below which the flow remains a streamline flow is known as

(A) relative velocity

(B) terminal velocity

(D) particle velocity

144. An electric bulb marked as 50 W-200 V is connected across a 100 V supply. The present power of the bulb is

(A) 37.5 W

(B) 25 W

(D) 10 W

151. A body is floating in a liquid at rest. Incorrect statement about situation options:

(A) Buoyancy is equal to weight of body.

(B) Weight of liquid displaced by body is equal to buoyancy.

(D) Weight will be greater than buoyancy.

152. The noise level during plane take off is around

(A) 100 dB

(B) 150 dB

(D) 250 dB

172. The potential energy of a molecule on the surface of a liquid compared to one inside the liquid is

(A) zero

(B) lesser

(D) greater

173. For a metallic wire, the ratio ^v/_i[ v = applied potential difference and i = current flowing ] is

(A) independent of temperature.

(B) increases as the temperature rises.

(D) increases or decreases as the temperature rises depending upon the metal.

193. The value of the compressibility of an ideal fluid is

(A) zero

(B) unity

(D) more than that of a real fluid

194. In electromagnetic theory, continuity equation relates _____

(A) volume conservation

(B) mass conservation

(D) energy conservation

195. Which is the cheapest device for measuring flow/discharge rate?

(A) Venturimeter

(B) Pitot tube

(D) None of the above

WBCS Main Question Paper – 2018

25. If the current passing through a resistance increase by two times, the heat generated will increase by

a) 2 times

b) 4 times

c) 6 times

d) 8 times

26. Atomic defect responsible for reduction of bulk density of the material :

a) Schottky

b) Frankel

c) Interstitial

d) Electronic

27. Largest amount of energy, the earth receiving from the sun is in the form of

a) Infrared and heat energy

b) Y -rays

c) UV-rays

d) X-rays

31. Electric power has the unit of

a) Volt

b) Watt

c) Coulomb

d) Ampere

35. Which material is used for production of automobile spring requiring high elastic property ?

a) Copper

b) Steel

c) Brass

d) All of the above

36. Sound wave having frequency more than 20,000 Hertz is known as

a) Ultrasonic

b) Supersonic

c) Microwave

d) Seismic

37. Spin of ‘Boson’ particle is equal to

a) positive integer

b) negative integer

c) positive integral multiple of ¹/₂

d) any fraction

39. Walk on a smooth floor causes fatal fall because

a) grip of legs with the floor surface minimizes

b) frictional force nil

c) centre of gravity of body changes

d) increase of forwarding forces

43. Quality of a musical note depends on

a) fundamental frequency

b) harmonics

c) amplitude of the wave

d) velocity of sound

44. Wavelength of visible light lies in between

a) 400 to 800 mm

b) 500 to 1000 mm

c) 300 to 600 mm

d) 200 to 400 mm

45. The device that converts AC to DC is called

a) Transformer

b) Rectifier

c) Induction motor

d) Dynamo

79. The electrical resistivity of a semiconductor

a) increases with temperature.

b) decreases with temperature

c) does not change with temperature.

d) increases at lower temperature but decreases at higher temperature.

73. A Carnot engine operating between 27°C and 127°C has efficiency:

a) 21%

b) 22%

c) 24%

d) 25%

75. The pressure gauge used for measuring very low vacuum of the order of lO torr:

a) Bourdon pressure gauge

b) Hot filament ionisation gauge

c) McLeod gauge

d) Inclined tube manometer

92. The resistance of an ideal ammeter is

a) zero

b) small

c) high

d) very high

93. Solar spectrum is the example of

a) continuous emission spectrum

b) band absorption spectrum.

c) line absorption spectrum

d) continuous absorption spectrum.

195. Worst possible rays responsible for cell mutation and cancer:

(A) ß-rays

(B) α-rays

(D) X-rays

WBCS Main Question Paper – 2017

51. An internal combustion engine runs on the principle of

(A) Otto cycle

(B) Diesel cycle

(D) Ranking cycle

52. Who presented first the experimental value of G ?

(1798)

(A) Newton

(B) Cavendish

(D) None of the above

54. When the milk is churned vigorously, the cream is separated due to

(A) Fractional force

(B) Centrifugal force

(D) Gravitational force

55. Weber is the unit of

(A) Intensity of magnetization

(B) Permeability

(D) Magnetic susceptibility

56. One nano meter is equal to

(A) 10-15 m

(B) 10-9 m

(D) 10-12 m

153. Water attains maximum density at

(A) 0°C

(B) 4°F

(D) 4°C

154. If two bulbs of 25 W and 100 W rated at 220 V, are connected in series across 440 V supply

(A) 25 W bulb will fuse

(B) 100 W bulb will fuse

(D) Both will fuse.

156. If the lengths and two diagonals of a rectangle are each increased by 6%, find % increase in its breadth.

(A) 5%

(B) 6%

(D) 8%

157. The aspect ratio is the ratio of

(A) x axis : y axis

(B) Sinθ : Cosθ

(D) None of the above

158. Refractive index of a medium is defined by

(A) the ratio of the cosine of the angles of incidence and refraction of light is constant when it passes between two given media.

(B) the ratio of the sine of the angles of refraction and incidence of light is constant when it passes between two given media.

(C) the ratio of the sine of the angles of incidence and refraction of light is constant when it passes between two given media.

(D) None of the above

173. The Crown glass is an

(A) Optical glass

(B) Radiation shield glass

(D) Toughened glass

174. An intrinsic semiconductor has forbidden gap of

(A) 2eV

(B) >2eV

(D) None of the above

177. The specific gravity of ß-quartz is

(2.65 g/cc, 2.59 to 2.63 in impure varieties)

(A) 2.32 g/cc

(B) 2.63 g/cc

(D) 2.2 g/cc

195. (Ni-Mn) ferrite is the example of material

(A) ferrimagnetic

(B) paramagnetic

(D) None of the above

196. Soft iron is used in many parts of electrical machines for its

(A) Low hysteresis loss and low permeability

(B) High hysteresis loss and low permeability

(D) Low hysteresis loss and high permeability

197. Tangent galvanometer is used to measure

(A) Steady currents

(B) Currents impulses

(D) None of the above

198. In a charged capacitor, the energy is stored as

(A) Positive charge

(B) both as positive and negative charge

(D) the potential energy of the capacitor plates

199. Line spectrum is produced by

(A) the Sun

(B) mercury vapour lamp

(D) electric bulb

WBCS Main Question Paper – 2016

8. The electrical circuits used to get smooth D.C. output from a rectified circuit is called –

(A) amplifier

(B) filter

(D) full wave rectifier

11. Which one among the following has the highest energy ?

(A) Blue light

(B) Green light

(D) Yellow light

12. Cylindrical lens is used by a person suffering from –

(A) astigmatism

(B) myopia

(D) pres biopia

13. To an observer on the lunar surface, during the day time the sky will appear to be –

(A) light yellow

(B) orange

(D) black

14. What is viewed through an electron microscope ?

(A) Electrons and other elementary particles

(B) Structure of bacteria and viruses

(D) Inside of the human eye

15. When viewed in white light, soap bubbles show colours because of –

(A) scattering

(B) diffraction

(D) dispersion

16. In electric supply lines in India, which parameter is kept constant ?

(50 Hz)

(A) Voltage

(B) Current

(D) Power

17. What is the most commonly used substance in fluorescent tubes ?

(A) Sodium oxide and argon

(B) Sodium vapour and neon

(D) Mercury oxide and neon

18. Which one of the following is printed on a commonly used fluorescent tube light ?

(Color temperature)

(A) 220 K

(B) 275 K

(D) 9000 K

19. Electricians use rubber glaves while working because –

(A) rubber is a good conductor

(B) rubber is an insulator

(D) None of the above

20. Which type / types of pen uses / use capillary action in addition to gravity for flow of ink ?

(A) Fountain pen

(B) Ball point pen

(D) Both ball point and gel pens

21. Parsec is a measure of –

(3.26156 light year)

(A) brightness of heavenly bodies

(B) density of the earth

(D) astronomical distance

26. Which of the following Persons discovered the gamma rays ?

(from radium in 1900)

(A) Paul Villard

(B) Marie Curie

(D) Adam Osborne

27. 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

(D) the mass of the fundamental particles

29. When red glass is heated in dark room it will seem –

(A) green

(B) purple

(D) yellow

30. A refrigerator, with its power on, is kept in closed room with its door open. The temperature of the room will –

(A) fall

(B) rise

(D) None of these

31. Cooking taken longest time –

(A) at Shimla

(B) at Mt. Everest

(D) None of these

50. The mass-energy relation is the outcome of –

(A) quantum theory

(B) general theory of relativity

(D) special theory of relativity

51. Who firstly demonstrated experimentally the existence of electromagnetic waves ?

(A) Hertz(Germany)

(B) Romar

(D) Maxwell

53. Silica in amorphous form is used in –

(A) photovoltaic cell

(B) conductivity cell

(D) None of these

57. Fat can be separated from milk in a cream separator because of

(A) cohesive force

(B) gravitational force

(D) centrifugal force

70. If the earth was stop rotating, the value of ‘g’ –

(Equator – increases, Poles – unchanged)

(A) Increases

(B) decreases

(D) becomes zero

76. The celsius temperature is a / an –

(A) relative temperature

(B) absolute temperature

(D) approximate temperature

77. Weightlessness experienced in spaceship is due to

(A) absence of inertia

(B) absence of accelerating force

(D) free fall of the spaceship

82. The internal resistance of a dry cell is-

(A) equal to that of electrolytic cell

(B) smaller than that of electrolytic cell

(D) zero

83. Which of the following is the example of ideal black body ?

(A) Blackboard

(B) Kajol

(D) None of the above

84. REM is a unit of –

(Roentgen equivalent man)

(A) radiation dosage

(B) binding energy

(D) radioactivity

95. Entropy change of a system and its surroundings in equilibrium –

(A) increases

(B) decrease

(D) either increases or decreases

104. A small and a large rain drops are falling through air –

(A) the small drop moves faster

(B) the large drop moves faster

(D) None of the above

105. If a bomb dropped from an airplane explodes in midair –

(A) its kinetic energy increases

(B) its total energy increases

(C) its total kinetic energy decreases

(D) None of these

67. Which of the following is a closed system ?

(A) Jet engine

(B) Tea placed in steel kettle

(D) Rocket engine during propulsion

107. Nights are cooler in the deserts than in the plain because –

(albedo)

(A) sand radiate heat more quickly than the earth

(B) the sky remains clear most of the time

(D) None of the above

114. Which of the following is used by the mountaineers and the pilots to measure pressure ?

(A) Simple barometer

(B) Fortin’s barometer

(D) Aneroid barometer

124. Red shifts is an illustration of –

(A) high frequency absorption

(B) low temperature emission

(D) unknown phenomenon

125. What is the principle by which a cooling system (radiator) in a motor car works ?

(A) Convection

(B) Conduction only

(D) Both conduction and radiation

WBCS Main Question Paper – 2015

1. Diffusion of light in atmosphere takes place due to

(A) Dust Particles

(B) Carbon dioxide

(D) Water Vapour

2. A weightless rubber balloon is filled with 200c.c. of water. Its weight in water is equal to

(A) 9.8/5 N

(B) 9.8/10 N

(D) Zero

3. A car is running on a road at a uniform speed of 60 km/h. The net resultant force on the car is

(1st Law of motion)

(A) Driving force in the direction of motion of the car

(B) Resistance force in the direction opposite to car’s motion

(D) Equal to Zero

7. Rainbow is produced when sunlight falls on drop of rain. The physical phenomena responsible for this are

1) Dispersion

2) Refraction

3) Internal reflection

(A) 1 & 2

(B) 2 & 3

(D) All of the above

44. David Bushnell is credited with the creating of

(A) First submarine (1775)

(B) Hovercraft

(D) Catamaron

45. Which one of the following is printed on a commonly used fluorescent tube light?

(A) 220 K

(B) 273 K

(D) 9000 k

5. Who among the following scientists shared the Nobel Prize in Physics with Son

(A) Max Planck

(B) Albert Einstein

(D) Enrico Fermi

43. Sir C.V. Raman was awarded Nobel prize in the year

(Raman effect – light scattering)

(A) 1920

(B) 1925

(D) 1931

92. A sample of gas expands from volume V1 to V2. The amount of work done by gas is greatest when the expansion is

(A) Adiabatic

(B) Equal in all cases

(D) Isobaric

93. Blue colour of the sky is due to the phenomenon of

(A) Scattering

(B) Dispersion

(D) Refraction

94. Electron Volt is the unit of

(A) Potential difference

(B) Charge

(D) Power

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

(A) Power

(B) Wavelength

(D) Frequency

97. Fluorescent tubes are fitted with a choke. the choke coil

(A) Steps up the line voltage

(B) Steps down the line voltage

(D) Chekes low frequency current

98. 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

(B) Very Very low size

100. If the radius of the Earth were to shrink by one percent its mass remaining the same the value of ‘g’ on the earth’s surface would

(A) Increase by 0.5%

(B) Increase by 2.0%

(D) Decrease by 2.0%

184. Several colours on the screen of colour television are produced by mixing lights of colours

(A) red, yellow green

(B) Red, yellow, Blue

(D) Yellow, Green, Blue

WBCS Main Question Paper – 2014

1. Newton’s third law gives directly the law of conservation of

(A) Momentum

(B) Energy

(D) Power

11. The wave length of visible light lies between

(about 380 to 740 nanometers)

(A) 200 – 400 nm.

(B) 400 – 700 nm.

(D) 1000- 2000 nm.