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Science Environment And Technology – Yearwise Questions – Physics – W.B.C.S. Mains Examination.
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WBCS Main Question Paper – 2019
- Which of these are used to measure optical activity?
(A) Polarimeter
(B) Planometer
(C) Psychrometer
(D) Photometer - Black holes were predicted by
(A) Copernicus
(B) Einstein
(C) Rutherford
(D) Satyen Bose - 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
(C) Balmer, ultraviolet
(D) Balmer, visible - 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
(C) 10 cm
(D) 5 cm - Which of the following electromagnetic waves have the smallest
wavelength?
(A) Infrared rays
(B) UV rays
(C) X-rays
(D) y-rays - 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
(C) super conductor
(D) insulator - 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
(C) Moment of inertia and moment of a force
(D) Energy and torque - In which of the following phenomena, the heat waves travel along
straight lines with the speed of light?
(A) Thermal conduction
(B) Forced convection
(C) Natural convection
(D) Thermal radiation - 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
(C) 12.5 W
(D) 10 W - 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.
(C) Force applied by body on liquid is buoyancy downward.
(D) Weight will be greater than buoyancy. - 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
(C) critical velocity
(D) particle velocity - The noise level during plane take off is around
(A) 100 dB
(B) 150 dB
(C) 200 dB
(D) 250 dB - For a metallic wire, the ratio / [ v = applied potential difference and i =
current flowing ] is
(A) independent of temperature.
(B) increases as the temperature rises.
(C) decreases as the temperature rises.
(D) increases or decreases as the temperature rises depending upon the metal. - The value of the compressibility of an ideal fluid is
(A) zero
(B) unity
(C) infinity
(D) more than that of a real fluid - The potential energy of a molecule on the surface of a liquid compared
to one inside the liquid is
(A) zero
(B) lesser
(C) equal
(D) greater - In electromagnetic theory, continuity equation relates _____
(A) volume conservation
(B) mass conservation
(C) charge conservation
(D) energy conservation - Which is the cheapest device for measuring flow/discharge rate?
(A) Venturimeter
(B) Pitot tube
(C) Orifice Meter
(D) None of the above
WBCS Main Question Paper – 2018
- 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 - 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 - Electric power has the unit of
a) Volt
b) Watt
c) Coulomb
d) Ampere - Atomic defect responsible for reduction of bulk density of the material
a) Schottky
b) Frankel
c) Interstitial
d) Electronic - Which material is used for production of automobile spring requiring high elastic property ?
a) Copper
b) Steel
c) Brass
d) All of the above - Sound wave having frequency more than 20,000 Hertz is known as
a) Ultrasonic
b) Supersonic
c) Microwave
d) Seismic - 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 - Quality of a musical note depends on
a) fundamental frequency
b) harmonics
c) amplitude of the wave
d) velocity of sound - Spin of ‘Boson’ particle is equal to
a) positive integer
b) negative integer
c) positive integral multiple of 1 /2
d) any fraction - 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 - The device that converts AC to DC is called
a) Transformer
b) Rectifier
c) Induction motor
d) Dynamo - 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. - A Carnot engine operating between 27°C and 127°C has efficiency:
a) 21%
b) 22%
c) 24%
d) 25% - The resistance of an ideal ammeter is
a) zero
b) small
c) high
d) very high - Solar spectrum is the example of
a) continuous emission spectrum
b) band absorption spectrum.
c) line absorption spectrum
d) continuous absorption spectrum. - 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 - Worst possible rays responsible for cell mutation and cancer:
(A) ß-rays
(B) α-rays
(C) γ-rays
(D) X-rays
WBCS Main Question Paper – 2017
- Who presented first the experimental value of G ?
(1798)
(A) Newton
(B) Cavendish
(C) Galileo
(D) None of the above - When the milk is churned vigorously, the cream is separated due to
(A) Fractional force
(B) Centrifugal force
(C) Centripetal force
(D) Gravitational force - Weber is the unit of
(A) Intensity of magnetization
(B) Permeability
(C) Magnetic flux
(D) Magnetic susceptibility - An internal combustion engine runs on the principle of
(A) Otto cycle
(B) Diesel cycle
(C) Carnot cycle
(D) Ranking cycle - One nano meter is equal to
(A) 10-15 m
(B) 10-9 m
(C) 10-18 m
(D) 10-12 m - Water attains maximum density at
(A) 0°C
(B) 4°F
(C) 4 K
(D) 4°C - 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
(C) None of these will fuse
(D) Both will fuse. - If the lengths and two diagonals of a rectangle are each increased by
6%, find % increase in its breadth.
(A) 5%
(B) 6%
(C) 7%
(D) 8% - The aspect ratio is the ratio of
(A) x axis : y axis
(B) Sinθ : Cosθ
(C) Length : Width
(D) None of the above - 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 - The Crown glass is an
(A) Optical glass
(B) Radiation shield glass
(C) Safety glass
(D) Toughened glass - An intrinsic semiconductor has forbidden gap of
(A) 2eV
(B) >2eV
(C) <2eV (0.7 eV)
(D) None of the above - 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
(C) 2.53 g/cc
(D) 2.2 g/cc - (Ni-Mn) ferrite is the example of material
(A) ferrimagnetic
(B) paramagnetic
(C) ferromagnetic
(D) None of the above - 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
(C) Large density and large retentively
(D) Low hysteresis loss and high permeability - Tangent galvanometer is used to measure
(A) Steady currents
(B) Currents impulses
(C) Earth’s magnetic field
(D) None of the above - In a charged capacitor, the energy is stored as
(A) Positive charge
(B) both as positive and negative charge
(C) the electric field between the plates
(D) the potential energy of the capacitor plates - Line spectrum is produced by
(A) the Sun
(B) mercury vapour lamp
(C) candle
(D) electric bulb
WBCS Main Question Paper – 2016
- The electrical circuits used to get smooth D.C. output from a rectified
circuit is called –
(A) amplifier
(B) filter
(C) oscillator
(D) full wave rectifier - Which one among the following has the highest energy ?
(A) Blue light
(B) Green light
(C) Red light
(D) Yellow light - Cylindrical lens is used by a person suffering from –
(A) astigmatism
(B) myopia
(C) hypermetropia
(D) pres biopia - To an observer on the lunar surface, during the day time the sky will
appear to be –
(A) light yellow
(B) orange
(C) blue
(D) black - What is viewed through an electron microscope ?
(A) Electrons and other elementary particles
(B) Structure of bacteria and viruses
(C) Inside of human stomach
(D) Inside of the human eye - When viewed in white light, soap bubbles show colours because of –
(A) scattering
(B) diffraction
(C) interference
(D) dispersion - In electric supply lines in India, which parameter is kept constant ?
(50 Hz)
(A) Voltage
(B) Current
(C) Frequency
(D) Power - What is the most commonly used substance in fluorescent tubes ?
(A) Sodium oxide and argon
(B) Sodium vapour and neon
(C) Mercury vapour and argon
(D) Mercury oxide and neon - Which one of the following is printed on a commonly used fluorescent
tube light ?
(A) 220 K
(B) 275 K
(C) 6500 K
(D) 9000 K - Electricians use rubber glaves while working because –
(A) rubber is a good conductor
(B) rubber is an insulator
(C) it is easy to work while wearing gloves
(D) None of the above - Which type / types of pen uses / use capillary action in addition to
gravity for flow of ink ?
(A) Fountain pen
(B) Ball point pen
(C) Gel pen
(D) Both ball point and gel pens - Parsec is a measure of –
(A) brightness of heavenly bodies
(B) density of the earth
(C) orbital velocity of the stars
(D) astronomical distance - Which of the following Persons discovered the gamma rays ?
(from radium in 1900)
(A) Paul Villard
(B) Marie Curie
(C) J. J. Thompson
(D) Adam Osborne - 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 - When red glass is heated in dark room it will seem –
(A) green
(B) purple
(C) black
(D) yellow - 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
(C) remain the same
(D) None of these - Cooking taken longest time –
(A) at Shimla
(B) at Mt. Everest
(C) at the sea level
(D) None of these - 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 - Who firstly demonstrated experimentally the existence of
electromagnetic waves ?
(A) Hertz (Germany)
(B) Romar
(C) Marconi
(D) Maxwell - Silica in amorphous form is used in –
(A) photovoltaic cell
(B) conductivity cell
(C) standard hydrogen electrode
(D) None of these - Fat can be separated from milk in a cream separator because of
(A) cohesive force
(B) gravitational force
(C) centripetal force
(D) centrifugal force - If the earth was stop rotating, the value of ‘g’ –
(Equator – increases, Poles – unchanged)
(A) Increases
(B) decreases
(C) remain unchanged
(D) becomes zero - The celsius temperature is a / an –
(A) relative temperature
(B) absolute temperature
(C) specific temperature
(D) approximate temperature - Weightlessness experienced in spaceship is due to
(A) absence of inertia
(B) absence of accelerating force
(C) absence of gravity
(D) free fall of the spaceship - The internal resistance of a dry cell is-
(A) equal to that of electrolytic cell
(B) smaller than that of electrolytic cell
(C) higher than that of electrolytic cell
(D) zero - Which of the following is the example of ideal black body ?
(A) Blackboard
(B) Kajol
(C) A pin hole box
(D) None of the above - REM is a unit of –
(Roentgen equivalent man)
(A) radiation dosage
(B) binding energy
(C) packing fraction
(D) radioactivity - Entropy change of a system and its surroundings in equilibrium –
(A) increases
(B) decrease
(C) remains constant
(D) either increases or decreases - A small and a large rain drops are falling through air –
(A) the small drop moves faster
(B) the large drop moves faster
(C) both moves with same speed
(D) None of the above - 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 - Which of the following is a closed system ?
(A) Jet engine
(B) Tea placed in steel kettle
(C) Pressure cooker
(D) Rocket engine during propulsion - 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
(C) sand absorbs heat quickly than the earth
(D) None of the above - Which of the following is used by the mountaineers and the pilots to
measure pressure ?
(A) Simple barometer
(B) Fortin’s barometer
(C) Manometer
(D) Aneroid barometer - Red shifts is an illustration of –
(A) high frequency absorption
(B) low temperature emission
(C) doppler effect
(D) unknown phenomenon - What is the principle by which a cooling system (radiator) in a motor
car works ?
(A) Convection
(B) Conduction only
(C) Radiation only
(D) Both conduction and radiation
WBCS Main Question Paper – 2015
- Diffusion of light in atmosphere takes place due to
(A) Dust Particles
(B) Carbon dioxide
(C) Helium
(D) Water Vapour - A car is running on a road at a uniform speed of 60 km/h. The net resultant force on the car is
(A) Driving force in the direction of motion of the car
(B) Resistance force in the direction opposite to car’s motion
(C) An inclined force
(D) Equal to Zero
- 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
(C) 1 & 3
(D) All of the above - 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
(C) 9.8/2 N
(D) Zero - David Bushnell is credited with the creating of
(A) First submarine (1775)
(B) Hovercraft
(C) Steamship
(D) Catamaron - Which one of the following is printed on a commonly used fluorescent
tube light?
(A) 220 K
(B) 273 K
(C) 6500 K
(D) 9000 k - Who among the following scientists shared the Nobel Prize in Physics with Son
(A) Max Planck
(B) Albert Einstein
(C) William Henry Bragg (1915)
(D) Enrico Fermi - Sir C.V. Raman was awarded Nobel prize in the year
(Raman effect – light scattering)
(A) 1920
(B) 1925
(C) 1930
(D) 1931 - 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
(C) Isothermal
(D) Isobaric - Blue colour of the sky is due to the phenomenon of
(A) Scattering
(B) Dispersion
(C) Reflection
(D) Refraction - Electron Volt is the unit of
(A) Potential difference
(B) Charge
(C) Energy
(D) Power - Photoelectric emission occurs only when the incident light has more than a certain minimum
(A) Power
(B) Wavelength
(C) Intensity
(D) Frequency - Fluorescent tubes are fitted with a choke. the choke coil
(A) Steps up the line voltage
(B) Steps down the line voltage
(C) Reduces the current in the circuit
(D) Chekes low frequency current - Several colours on the screen of colour television are produced by
mixing lights of colours
(A) red, yellow green
(B) Red, yellow, Blue
(C) Red, Green, Blue
(D) Yellow, Green, Blue - 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
(B) Very Very low size - 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%
(C) Decrease by 0.5%
(D) Decrease by 2.0%
WBCS Main Question Paper – 2014
- The wave length of visible light lies between
(about 380 to 740 nanometers)
(A) 200 – 400 nm.
(B) 400 – 700 nm.
(C) 700 – 1000 nm.
(D) 1000- 2000 nm. - Newton’s third law gives directly the law of conservation of
(A) Momentum
(B) Energy
(C) Angular Momentum
(D) Power
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