Physics & Technology

WBCS Prelims – 2018
54. All electromagnetic wave have the same
(c)wavelength in vacuum
(d) speed in vacuum
58. The speed of sound is faster in
66. If we add salt to pure water, its boiling point will
(c)remains same
(d)None of the above
74. Short-sight defect could be corrected by a
(a)Convex lens
(b)Concave Lens
(c)Converging lens
(d)None of the above
79. Red + Green + Blue =?
109) A combination of 16 bits is called
(a) word
(b) nibble
(c) memory block
(d) byte
113) A stone tied to a string is whirled in a circle . As it was revolving, the rope suddenly snaps. Then
(a) The stone flies off tangentially
(b) The stone moves radially outward
(c) The stone moves radially inward
(d) None of the above
119) A body is floating in a liquid partly immersed. The body and the liquid are taken to moon. The body
(a) will continue to float as before
(b) floats with greater part immersed
(c) floats with lesser part immersed
(d) will sink
123) USB is which type of storage device?
(a) Primary
(b) Secondary
(c) Tertiary
(d) None of the above
130) Which among the following is commonly used language in Android applications?
(a) Java
(b) C++
(c) C
(d) PHP
135) Errors in computer programme is called
(a) Spam
(b) Follies
(c) Virus
(d) Bugs
WBCS Prelims – 2017
27. 1 nm is equivalent to   
(A) 10 A   
(B) 100 A   
(C) 10 micron    .
(D) 01 mm    A
44.  RADAR’ stands for   
Radio Detection and Ranging
Ready Advanced Appliance for Ranging   
Range Detection Appliance Ranging   
Ready Advanced Airplane Ranging  
45.  A body is acted upon by two unequal forces in opposite directions, but not in one line. The effect is that the will have   
(A) only rotational motion   
(B) only translational motion    
(C) neither the rotational nor the translational motion   
(D) rotational as well as translational motion   
46.  A shaving brush is dipped in water. When taken out the hairs of the brush are seen to be drawn together due to   
(A) surface tension of water 
(B) viscosity of water   
(C) elasticity of hair of the brush   
(D) temperature difference between air and water  
47    Red’ is used as a danger signal because   
(A) blood is red   
(B) red light is scattered least by the air molecules
(C) red colour is easily available   
(D) red colour is soothing for eye   
48.  The immersed portion of a piece of pure ice floating in water is   
8/9 the of its volume   
9/10th of its volume  
10/12th of volume   
11/12 of volume
49. The electric appliances in a house are connected   
(A) in series   
(B) in parallel
(C) either in series or in parallel   
(D) both in series and in parallel   
WBCS Prelims – 2016
77.   X-rays are
(A) electromagnetic radiations of very short wavelength
(B) beams of electrons
(C) electromagnetic radiations of very long wavelength
(D) visible to the naked eye
82.  Astronomy means study of the —
(A) Moon      (B) Stars        
(C) Sky         (D) Sun
83.  Water rises up a capillary tube because of—
(A) Elasticity       
(B) Surface tension       
(C) Viscosity       
(D) its density
85.  The image formed by a plane mirror is —
(A) real and erect      
(B) virtual and inverted        
(C) virtual and erect      
(D) real and inverted
88.  The energy radiated by the Sun is because of—
(A) Nuclear fusion      
(B) Nuclear fission      
(C) Radioactive decay      
(D) Photo-electric effect
91.  With increase in temperature the resistance of a pure semiconductor —
(A) first increases and then decreases       
(B) remains the same
(C) increases        
(D) decreases
94.  Which of the following is not a conservative force ?
(A) Gravitational force       
(B) Frictional force      
(C) Electrostatic force     
(D) Magneto static force
105.  The heat of the sun reaches us by —
(A) Conduction        
(B) Convection        
(C) Radiation       
(D) None of the above
WBCS Prelims – 2015
85.  The solar cooker works on the same principle as
(A) Bolometer        
(B) Pyrometer        
(C) Greenhouse        
(D) Galvanometer
88. Hydraulic press is based on
(A) Archimedes’ law        
(B) Pascal’s law       
(C) Reynold’s law       
(D) Bernouli law
91. LED stands for
(A) Light emitting device      
(B) Light emitting diode    
(C) light encapsulated device    
(D) light emitting dots
94.   At what temperature, Celcius and Fahrenheit readings will be same ?
(A) + 40°       (B) + 20°     
(C) – 20°       (D) – 40°
105.  When a ball is taken from the equator to the pole of the earth
(A) Its mass increases     
(B) Both its mass and weight change
(C) Its weight increases      
(D) Its weight decreases
WBCS Prelims – 2014
31.  Compound microscope has
(A) two lenses     
(B) requires UV light source
(C) used to view only dead organisms      
(D) requires large room space
92.  Among the following select the odd one.
(A) Metre      
(B) Furlong        
(C) Acre      
(D) Mile
107.  Which of the rays is most dangerous  ?
(A) Alpha ray      
(B) Beta ray        
(C) Gama ray      
(D) X-ray
115.   RADAR is used for
(A) locating submerged submarines.
(B) receiving signals in a radio receiver.
(C) locating geostationary satellites.
(D) detecting and locating the position of objects such as aeroplane.
119.   Sound waves in air are
(A) Transverse       
(B) Longitudinal       
(C) Electromagnetic      
(D) Polarized
123.   LCD stands for
(A) Liquid Crystal Display      
(B) Low Current Display
(C) Light Circuit Display      
(D) None of the above
142.  Basically domestic electric wiring is a
(A) parallel connection      
(B) series connection
(B) combination of series and parallel connections      
(D) None of the above
171.  Optical fibre works on the
(A) Principle of Refraction       
(B) Total Internal Reflection      
(C) Scattering      
(D) Reflection
WBCS Prelims – 2013
26.  Dyne-sec, stands for the unit of :
(A) Force     
(B) Momentum       
(C) Energy      
(D) Power
30.  For the same Kinetic energy, the momentum shall be maximum for :
(A) Electron     
(B) Proton      
(C) Deuteron       
(D) Alpha particle
34.  An ice cube containing a large bubble of air is floating in water contained in a large beaker. When the ice melts completely, the level of water will :
(A) Remain unchanged       
(B) Go down       
(C) Rise       
(D) First rise and then go down
42.  Water is boiling in a flask over a burner. To reduce its boiling temperature one must —
(A) Reduce the surrounding temperature
(B) Connect the mouth of the flask to an evacuating system
(C) Supply heat from a less intense source
(D) Connect the mouth of the flask to a compressor
58.  Instruments can be shielded from the effects of external magnetic fields by surrounding them with —
(A) A glass shield       
(B) A rubber shield      
(C) A brass shield     
(D) An iron shield
WBCS Prelims – 2012
62.  The first remote sensing satellite from India was :
(A) P6     
(B) P4       
(C) IRS 1A      
69.  Arial photographs are studied wiih the help of :
(A) Microscope      
(B) Stereoscope        
(C) Parallax bar      
(D) Theodolite
107.  An object moving with a constant speed on a horizontal surface will not have :
(A) Velocity      
(B) Momentum       
(C) Kinetic energy       
(D) Acceleration
111.  Which of the following is not the unit of length ?
(A) Light year      
(B) Micron       
(C) AU       
(D) Radian
115.  Which surface is good absorber of heat ?
(A) White rough surface       
(B) Black rough surface
(C) White smooth surface     
(D) Black smooth surface
119.   Absolute Zero temperature is that temperature where :
(A) Water freezes to ice         
(B) All molecules of water comes to rest
(C) All matter stays in the solid state
(D) Kinetic and potential energies of the molecules become equal to each other
123.  A clear piece of glass immersed in a glycerol cannot be seen separately because in comparison to the refractive index of glycerol , the refractive index of glass is :
(A) Greater         
(B) Lesser        
(C) Nearly equal       
(D) This does not depend on the refractive index
130.   Gold has extraordinarily high density than silver, the reason is :
(A) Higher mass number of gold       
(B) Higher atomic number of gold
(C) High screening effect        
(D) Lanthanide contraction
142.  When a positively charged conductor is earthed, then –
(A) Electrons flow from conductor to earth       
(B) Protons flow from conductor to earth
(C) Electrons flow from earth to conductor       
(D) Protons flow from earth to conductor
149.  Which of the following waves is used for telecommunication ?
(A) Infra-red rays     
(B) Ultra violet rays       
(C) Micro waves      
(D) X-rays
WBCS Prelims – 2011
26.  An example of a scalar quantity is
(A) Velocity      
(B) Force      
(C) Momentum        
(D) Energy
34.  A piece of metal plate with a circular hole is heated.  If the metal plate expands on heating, the diameter of the hole will
(A) Increase      
(B) Decrease
(C) Increase or decrease depending on the diameter of the hole
(D) Increase or decrease depending upon the material of the plate
35.  The volume of a vessel containing an ideal gas is doubled and its temperature (in °K) is also doubled. The pressure of the gas
(A) Remains unchanged       
(B) Is doubled
(C) Is one-fourth of the original pressure
(D) Is four times the original pressure
54.  A spring has length l and spring constant K. It is cut into two pieces of lengths l1 and l2 . If l1 = nl2 , the spring constant of the spring of length l1 is
(A) K(l + n)/n      
(B) K(l + n)       
(C) Kn/(l + n)      
(D) K/(l + n)
55.  Two copper wires A and B have the same weight and the radius of B is half that of A .  The ratio RA/RB of their resistances is
(A) 1/4         (B) 1/8       
(C) 1/16       (D) 1/2
70.  The nuclear reaction involved in a nuclear reactor is
(A) Fission       
(B) Fusion       
(C) Spallation      
(D) Neutron absorption
71.  Dimension of gravitational constant is
(A) cm4 sec-1 gm-2      
(B) cm sec-3 gm-2       
(C) cm3 sec-2 gm-1     
(D) gm cm-3 sec-2
75.  The minimum distance between an object and its real image in a convex lens is
(A) More than 4f      
(B) Less than 4f        
(C) Equal to 2f       
(D) Equal to 4f
154.  Lowest rate of photosynthesis takes place in
(A) Blue light      
(B) Orange light       
(C) Green light       
(D) Red light
WBCS Prelims – 2010
28.  Rate of radiation of heat from a body is the highest if its surface is
(A) White       
(B) Smooth       
(C) Smooth but black       
(D) Rough but black
38.  The minimum number of artificial satellites required for communication throughout the globe is
(A) 1      (B) 2       
(C) 3      (D) 4
56.  A tube-well will not work if the depth of water below the ground is
(A) 20 ft.      (B) 25 ft.     
(C) 28 ft.      (D) 38 ft.
62.  Consider the following statement
(1) Definition of force is obtained from Newton’s first law of motion.
(2) Definition of force is obtained from Newton’s second law of motion.
(3) In a house-hold wiring the appliances are connected in series.
(4) The picture-tube of a television is basically a cathode ray tube.
(A) Only 1 is correct      
(B) Only 2 is correct
(C) Only 2 and 4 are correct       
(D) Only 1 and 4 are correct
76.  Electrical energy is converted into mechanical energy by a
(A) Thermostat        
(B) Motor       
(C) Dynamo       
(D) Rectifier
80.  A piece of cotton cloth gets wet if one end of it is dipped in water in a glass. This is due to
(A) Gravitation        
(B) Viscosity        
(C) Elasticity         
(D) Capillarity
185.  Same force is applied to two bodies A and B of masses m and 5 m respectively for the same time. Then
(A) Velocity of A and B will be same        
(B) Momentum of A and B will be same
(C) Momentum of A will be greater        
(D) Momentum of B will be greater
WBCS Prelims – 2009
30.  The weight of an object is
(A) Maximum at the centre of the earth
(B) Maximum at infinity
(C) Maximum at the surface of the earth
(D) Name everywhere from the center of the earth to infinity
34.  At constant temperature if the pressure decreases, then the volume of a given mass of gas will
(A) Increase       
(B) Decrease        
(C) Remain constant
(D) May increase or decrease depending on nature of the gas
38.  A small quantity of water is placed in a small cavity made in a block of ice at 0°C. What will happen to the water ?
(A) The water will freeze to ice at 0°C
(B) There will be no change in the temperature of water
(C) The temperature of water will decrease to 0°C but it will not freeze
(D) The water will freeze to ice if the block of ice is large compared to the mass of water
42.  The walls of a music hall should
(A) Transmit sound       
(B) Absorb sound     
(C) Reflect sound      
(D) Amplify sound
45.  The electromagnetic radiation that is emitted during the radio-active disintegration is
(A) X-rays       
(B) y-rays      
(C) Ultraviolet rays      
(D) Infra-red rays
69.  The reaction that occurs in nuclear reactors is
(A) Nuclear fusion      
(B) Spallation       
(C) Nuclear fission      
(D) Nuclear isomerisation
WBCS Prelims – 2008
101. The resistance of which of the following decreases with the rise of temperature ?
(A) Copper  
(B) Iron 
(C) Silicon  
(D) Mercury