Physics GK Quiz-27

Physics GK Quiz-27

Physics Multiple Choice Questions (MCQs) Quiz for State and UPSC Civil Services Examinations. Objective Questions on Physics for competitive examinations.

    521. It is easier for a man to swim in sea water, than in river water because

    (1) the density of sea water is lesser than the density of river water
    (2) the density of sea water is more than the density of river water
    (3) the sea is-deeper than the river
    (4) the sea is wider than the river
    Answer:
    521. (2) the density of sea water is more than the density of river water

    522. In the remote control of television, electromagnetic waves used are

    (1) ultraviolet 
    (2) microwave
    (3) radiowave 
    (4) infrared
    Answer:
    522. (4) All electromagnetic waves used are infrared.

    523. The waveform of a certain signal can be studied by

    (1) Spectrometer
    (2) Cathode ray oscilloscope
    (3) p – n junction diode
    (4) Sonometer
    Answer:
    523. (4) A spectrometer is an istrument used to measure properties of light over a specific portion of the
    electromagnetic spectrum. Cathode ray oscilloscope is an electronic display device containing cathode-ray tube (CRT) that generates an electron beam that is used to produce visible patterns or graphs on a phosphorescent screen. A sonometer is an apparatus made of hollow box having two holes. A string is attached to it by which the transverse vibrations of strings can be studied.

    524. A wire carrying current is

    (1) positively charged
    (2) negatively charged
    (3) neutral
    (4) charged with a type depending upon current strength
    Answer:
    524. (3) A wire carrying current is neutral.

    525. A light ray travelling from denser to rarer medium at an angle of incidence more than critical angle of concerned media pair suffers.

    (1) reflection
    (2) refraction
    (3) diffraction
    (4) total internal reflection
    Answer:
    525. (4) If the angle of incidence of light ray in the denser medium is greater than the critical angle of the concerned media pair, the light is not at all reflected in to the rarer medium but is totally reflected. This is known as ‘total internal reflection’.

    526. The characteristic invalid for heat radiation is that it travels :

    (1) in a straight line
    (2) in all directions
    (3) with the speed of light
    (4) heating the medium through which it passes
    Answer:
    526. (3) Heat is a form of energy. An important property of heat is that it flows from a body at higher temperature to another body at lower temperature.

    527. The method of magnetisation is:

    (1) hammering a magnet
    (2) heating a magnet
    (3) passing direct current through it
    (4) passing alternating current through it
    Answer:
    527. (1) Hammering a rod will either allow it to become slightly magnetic if laid along a magnetic field (i.e.North - South) or demagnetise it if laid across the field lines (i.e. East-West). A current passing through a coil will produce a magnetic field.

    528. Water is not suitable as a calorimetric substance because it :

    (1) has high specific heat
    (2) is a good conductor
    (3) has high boiling point
    (4) low latent heat of vapourization
    Answer:
    528. (1) The specific heat of water is higher than all other common substances. Hence, water is used for heating purposes (as in hot water bottles) and for cooling purposes (as in radiators of cars). Off all the liquids, mercury has the lowest specific heat due to which it is used as a thermometric liquid .

    529. When a body falls from an aeroplane, there is increase in its

    (1) Kinetic energy
    (2) Mass
    (3) Acceleration
    (4) Potential energy
    Answer:
    529. (3) The energy possessed by a body by virtue of its motion is called kinetic energy. Potential Energy is the energy possessed by virtue of its position or configuration. When a body falls from an aeroplane, there is increase in its acceleration.

    530. In a water lifting electric pump, we convert

    (1) Electrical energy into Potential energy
    (2) Kinetic energy into Electrical energy
    (3) Kinetic energy into Potential energy
    (4) Electrical energy into Kinetic energy
    Answer:
    530. (1) In a water lifting electric pump, we convert electrical energy into potential energy. In hydraulic pump mechanical energy in converted into potential energy.

    531. The type of mirror used in automobiles to see the traffic on the rear side is

    (1) Concave 
    (2) Plano-Convex
    (3) Plane 
    (4) Convex
    Answer:
    531. (4) Convex mirrors are used as rear view mirrors in automobiles to see the traffic on the rear side. A convex mirror always produces an erect image of the objects. The image formed in a convex mirror is highly diminished than the object, due to which a convex mirror gives a wide field of view of the traffic behind.

    532. Which, of the following radiations has the least wavelength ?

    (1) X-rays 
    (2) a-rays
    (3) g-rays 
    (4) b-rays
    Answer:
    532. (3) X-rays – smaller than 10 nano metre
    gamma- rays – 0.0005 to 0.1 nano metre
    alpha-rays – 125 nano metre

    533. The earth is a

    (1) good reflector of heat
    (2) non-absorber of heat
    (3) good absorber and good radiator of heat
    (4) bad absorber and bad radiator of heat
    Answer:
    533. (3) The earth’s surface radiates as a black body, since it aborts and radiates with nearly 100 percent
    efficiency for its temperatures. Gases, on the contrary, are selective absorbers and radiators.

    534. Magnetic keepers are pieces of

    (1) Nickel 
    (2) Cobalt
    (3) Steel 
    (4) Soft iron
    Answer:
    534. (4) Magnetic keepers are pieces of soft iron that are placed across the poles of a bar magnet or a horseshoe magnet. They help prevent the loss of magnetism.

    535. When a piece of stone is immersed in water, it displaces water of equal

    (1) Density
    (2) Specific gravity
    (3) Mass 
    (4) Volume
    Answer:
    535. (3) Archimedes’ Principle states that upward buoyant force exerted on a body immersed in a fluid is equal to the weight of the fluid the body displaces.

    536. The motion of a body that repeats itself after a regular interval of time is

    (1) a periodic motion
    (2) a simple harmonic motion
    (3) an aperiodic motion
    (4) an oscillatory motion
    Answer:
    536. (1) The motion of a body that repeats itself after a regular interval of time is called ‘Periodic Motion’. Simple Harmonic Motion is a type of periodic motion where the restoring force is directly proportional to the displacement.

    537. A radioactive substance does not undergo any change (in mass or charge) during

    (1) gamma-emission
    (2) oxidation
    (3) alpha-emission
    (4) beta-emission
    Answer:
    537. (1) Gamma-rays do not carry any charge. These rays do not have any mass and hence can not be considered to be made up of particles.

    538. One bar is equal to

    (1) 103 Pa 
    (2) 100 Pa
    (3) 105 Pa 
    (4) 104 Pa
    Answer:
    538. (3) The bar is a non-SI unit of pressure. It is defined by the IUPAC as exactly equal to 100,000 Pa or 105 Pa.

    539. Specific gravity is defined as the ratio of

    (1) density of the substance to the density of water
    (2) density of the substance to the density of water at 0°C
    (3) density of water at 4°C to the density of the substance
    (4) density of the substance to the density of water at 4°C
    Answer:
    539. (1) Specific gravity is the ratio of the density of a substance to the density (mass of the same unit volume) of a reference substance. The reference substance is nearly always water for liquids or air for gases.

    540. A barometer is kept inside a bell jar. Air is slowly pumped out of the jar.

    (1) The mercury level starts rising
    (2) The mercury level starts falling
    (3) The mercury level does not change
    (4) The bell jar breaks up
    Answer:
    540. (1) As the pump removes the air from the bell jar the pressure obviously reduces around the barometer. The reduction in pressure around the barometer leads it to expand. As the pump removes air from the jar, the mercury level rises.

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