Physics GK Quiz-36

Physics GK Quiz-36

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

    701. The abbreviation LHC stands for which machine ?

    (1) Light Heat Collider
    (2) Large Hadron Collider
    (3) Long Heavy Collider
    (4) Large High Collider
    Answer:
    701. (2) LHC stands for Large Hadron Collider is the world’s largest and most powerful particle collider that allows scientists to further test the properties of the Higgs boson. It lies in a tunnel beneath the France– Switzerland border near Geneva, Switzerland. It is the largest, most complex experimental facility ever built, and the largest single machine in the world.

    702. Which of these travels in glass with minimum velocity ?

    (1) red light 
    (2) violet light
    (3) green light 
    (4) yellow light
    Answer:
    702. (2) Red light has a longer wavelength than violet light and the other colours of visible light have intermediate wavelengths. As light passes from air into glass, there is reduction of velocity. Due to longer wavelengths, red waves travel fastest and is refracted the least, while violet waves travel the slowest and is refracted the most.

    703. The phenomenon which causes mirage is

    (1) Interference
    (2) Diffraction
    (3) Polarisation
    (4) Total internal reflection
    Answer:
    703. (4) Mirage is caused by total internal reflection in deserts where due to heating of the earth, refractive index of air near the surface of earth becomes lesser than above it. A ray of light coming from a distant object gets refracted from a denser to a rarer medium. Consequently the refracted ray bends away from the normal until at a particular layer, the light is incident at an angle greater than the critical angle. At this stage the incident ray suffers total internal reflection and is reflected upwards. When this reflected beam of light enters the eyes of the observer, it creates an illusion of the water near the object.

    704. Which of the following phenomenon helps to conclude that light is a transverse wave?

    (1) interference 
    (2) diffraction
    (3) polarisation 
    (4) refraction
    Answer:
    704. (3) The phenomena of interference and diffraction of light were successful beyond doubt to prove that light is a form of wave. But they failed to decide whether light is transverse or longitudinal wave. The fact that light is a transverse wave was established only after the discovery of the phenomenon of polarization. It was Huygens who first discovered the phenomenon of polarization in 1690. The phenomenon of interference and diffraction can be exhibited by all types of waves but polarization can be exhibited by the transverse waves only. So it was the discovery of polarization of light that helped us to prove that light is a transverse wave.

    705. Plank’s constant has the dimensions of :

    (1) energy
    (2) linear momentum
    (3) angular momentum
    (4) force
    Answer:
    705. (1) The Planck’s constant (h) can be defined as a proportionality constant that relates the energy (E) of a photon to the frequency (?) of its associated electromagnetic wave. Mathematically, Planck’s Constant (h) = Energy (E)/frequency (?). The Planck constant is named after Max Planck, the instigator of quantum theory, who discovered it in 1900

    706. Blowing Air with open pipe is an example of :

    (1) Isothermal process
    (2) Isochroric process
    (3) Isobaric process
    (4) Adiabatic process
    Answer:
    706. (3) When air is suddenly exhaled out into a larger volume through the narrow opening, air undergo adiabatic expansion. So blowing air is an adiabatic process. But since it is open pipe, the pressure inside
    and pressure outside remains same. So ultimately the process is isobaric.

    707. The amount of matter in a ball of steel is its :

    (1) Weight 
    (2) Mass
    (3) Density 
    (4) Volume
    Answer:
    707. (2) In simple terms, mass is the amount of matter in an object, and is measured in grams. Under normal circumstances, and as long as it remains intact, an object will always have the same mass, i.e. there will always be the same amount of matter in it. A steel ball will have the same amount of steel in it - its mass will be the same - whether it is on the Earth's surface or on the Moon.

    708. Unit of resistance is :

    (1) volt2× ampere
    (2) volt/ampere
    (3) ampere/volt
    (4) volt × ampere
    Answer:
    708. (2) An ohm (O) is the SI derived unit of electrical resistance. By definition, a conductor has an electrical resistance of one ohm when a constant potential difference of one volt applied between its ends produces in this conductor a current of one ampere. A volt per ampere (V/A) is the SI derived unit, which is equal to ohm by definition O = V/A.

    709. A cycle tyre bursts suddenly. This represents an :

    (1) Isothermal process
    (2) Adiabatic process
    (3) Isochoric process
    (4) Isoboric process
    Answer:
    709. (2) When a tyre bursts suddenly energy is not immediately transferred between the system and the surrounding. So the process is adiabatic. There sudden expansion of its air into the atmosphere is adiabatic and the tyre is cooled. In adiabatic process, heat neither enters the system nor leaves the system.

    710. In which region of electromagnetic spectrum does the Lyman series of hydrogen atom lie ?

    (1) Visible 
    (2) Infrared
    (3) Ultraviolet 
    (4) X-ray
    Answer:
    710. (3) In physics and chemistry, the Lyman series is a hydrogen spectral series of transitions and resulting ultraviolet emission lines of the hydrogen atom as an electron goes from n > 2 to n = 1 (where n is the principal quantum number) the lowest energy level of the electron. The first line in the spectrum of the Lyman series was discovered in 1906 by Harvard physicist Theodore Lyman, while studying the ultraviolet spectrum of electrically excited hydrogen gas. The rest of the lines of the spectrum (all in the ultraviolet) were discovered by Lyman from 1906-1914.

    711. A light wave is incident over a plane surface with velocity x. After reflection the velocity becomes :

    (1)x/2
    (2) x
    (3) 2x 
    (4)x/4
    Answer:
    711. (2) When a ray of light incident on a boundary separating two media comes back into the same media, this phenomenon, is called reflection of light. After reflection velocity, wavelength and frequency of light remains same but intensity decreases.

    712. Distant objects are visible as a little out of focus in this condition :

    (1) presbiopia
    (2) hypermetropia
    (3) astigmatism
    (4) myopia
    Answer:
    712. (4) Myopia, also known as near-sightedness and shortsightedness, is a condition of the eye where the light that comes in does not directly focus on the retina but in front of it, causing the image that one sees when looking at a distant object to be out of focus, but in focus when looking at a close object.

    713. The redness in atmosphere at Sunrise and Sunset is due to :

    (1) Refraction of light
    (2) Reflection of light
    (3) Dispersion of light
    (4) Scattering of light
    Answer:
    713. (4) The red colour in the sky at sunset (and sunrise) is due to an effect called Rayleigh scattering. At sunrise or sunset, since the Sun is low on the horizon, the light rays must pass through more of the atmosphere – and therefore bounce off more molecules – than at other times of day. Thus, blue light gets scattered away before the light reaches your eyes. Other colors – such as red, orange and yellow –continue to pass through the atmosphere unaffected.

    714. If density of oxygen is 16 times that of hydrogen, what will be their corresponding ratio of velocity of sound?

    (1) 4 : 1 
    (2) 2 : 1
    (3) 1 : 16 
    (4) 1 : 4
    Answer:
    714. (4) 

    715. S.I. unit of Magnetic flux is

    (1) weber 
    (2) weber/m
    (3) weber/m4 
    (4) weber–m2
    Answer:
    715. (1) The SI unit of magnetic flux is the Weber (Wb) (in derived units: volt-seconds). It is the magnetic flux that, linking a circuit of one turn, would produce in it an electromotive force of 1 volt if it were reduced to zero at a uniform rate in 1 second. It is named after the German physicist Wilhelm Eduard Weber. The CGS unit of magnetic flux is Maxwell.

    716. To prevent damage from lightning, lightning conductors are used on tall structures. The lightning conductor

    (1) should be made of a good conductor but can be of any shape
    (2) should be in the form of a vertical rod
    (3) can be of any shape
    (4) should be made of a good conductor like copper with sharp-pointed edges
    Answer:
    716. (4) A lightning conductor is made up of a sharp pointed metal (usually copper metal, as it is a very good conductor) connected directly to the ground. It is placed higher than the roof so that if lightning strikes, it strikes the conductor before it can reach the house. It should be pointed because when the negative charge is discharged by the cloud, it will first strike the pointed tip of the lightning conductor and quickly travel to the earth. The discharge will be quickly over and the house and its surroundings will be saved from damage. The pointed nature of the lightning conductor helps it to acquire more number of positive charges on its tip.

    717. Beta rays emitted by a radioactive material are

    (1) The electrons orbiting around the nucleus
    (2) Charged particles emitted by nucleus
    (3) Neutral particles
    (4) Electromagnetic radiations
    Answer:
    717. (2) A beta ray is a high-energy, high-speed electron (negatively charged) or positron (positively charged) emitted in the radioactive decay of an atomic nucleus, such as a potassium-40 nucleus, in the process of beta decay. Two forms of beta decay, b– and b+, respectively produce electrons and positrons. Beta radiation takes the form of either an electron or a positron being emitted from the nucleus of an atom.

    718. ‘Parsec’ is the unit measurement of

    (1) Density of stars
    (2) Astronomical distance
    (3) Brightness of heavenly bodies
    (4) Orbital velocity of giant stars
    Answer:
    718. (2) Parsec is a unit of distance used in astronomy to measure large distances to objects outside our Solar System. It is equal to about 3.26 light years (3.086 × 1013 kilometres). One parsec is the distance at which one astronomical unit subtends an angle of one arcsecond.

    719. The phenomenon of change in direction of light when it passes from one medium to another is called

    (1) Propagation
    (2) Reflection
    (3) Refraction
    (4) Dispersion
    Answer:
    719. (3) Refraction is the change in direction of wave propagation due to a change in its transmission medium.Due to the change of medium, the phase velocity of the wave is changed but its frequency remains constant. Refraction of light is the most commonly observed refractive phenomenon, but any type of wave can refract when it interacts with a medium.

    720. Super cooling stands for cooling of a liquid :

    (1) at freezing point
    (2) below freezing point
    (3) at melting point
    (4) above melting point
    Answer:
    720. (2) Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid. A good example of this phenomenon is clouds in high altitude that are an accumulation of supercooled droplets of water below their freezing point. Refrigeration is a popular commercial application of supercooling.

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