Physics GK Quiz-29

Physics GK Quiz-29

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

    561. Outside of cooking utensils are generally left black from below because

    (1) it is difficult to clean daily.
    (2) black surface is a good conductor of heat.
    (3) black surface is a poor conductor of heat.
    (4) black surface is a good absorber of heat.
    Answer:
    561. (4) The outside surface of a utensil used for heating is coated black so that it may absorb more heat and make heating quicker. This is because black surface is a good absorber of heat.

    562. The colour of sky appears blue due to

    (1) reflection 
    (2) refraction
    (3) scattering of shorter wave lengths
    (4) dispersion
    Answer:
    562. (3) The sunlit sky is blue because air scatters shortwavelength light more than longer wavelengths. Since blue light is at the short wavelength end of the visible spectrum, it is more strongly scattered in the atmosphere than long wavelength red light. The result is that the human eye perceives blue when looking toward parts of the sky other than the sun.

    563. What is a compound microscope?

    (1) A microscope that has one lens.
    (2) A microscope that has two sets of lenses : an occular lens and an eyepiece.
    (3) A microscope whose lenses are concave.
    (4) A microscope whose lenses are convex.
    Answer:
    563. (2) A compound microscope is a microscope which uses multiple lenses to collect light from the sample and then a separate set of lenses to focus the light into the eye or camera. The objective lens provides the primary magnification which is compounded (multiplied) by the ocular lens (eyepiece).

    564. Sensitivity of the human eye is maximum in the

    (1) Violet region 
    (2) Green region
    (3) Blue region 
    (4) Red region
    Answer:
    564. (2) The human eye is sensible to light wave which wavelength is roughly between 400 nm and 700 nm. When illumination is enough (in daylight) the maximum sensitivity is in the green region at 555 nm.

    565. The speed of light in air is

    (1) 3 × l08 m/s 
    (2) 3 × l 0–8 cm/s
    (3) 8 × l03 m/s 
    (4) Infinity
    Answer:
    565. (1) Speed of light (in Media) = Speed of Light (in Vacuum) / Refreactive Index of Material. Speed of light in air as taken generally is 3 X 10 power 8 meter per second.

    566. Photon is the fundamental unit/ quantum of

    (1) gravitation 
    (2) electricity
    (3) magnetism 
    (4) light
    Answer:
    566. (4) A photon is an elementary particle, the quantum of light and all other forms of electromagnetic
    radiation. The modern photon concept was developed gradually by Albert Einstein.

    567. A liquid disturbed by stirring comes to rest due to

    (1) density
    (2) surface tension
    (3) viscosity
    (4) centripetal force
    Answer:
    567. (3) It happens because of viscosity. The viscosity of a fluid is a measure of its resistance to gradual
    deformation by shear stress or tensile stress. It is due to friction between neighboring parcels of the
    fluid that are moving at different velocities.

    568. In Astrophysics, what name is given to a hypothetical hole in outer space from which stars and energy emerge?

    (1) Black hole 
    (2) Ozone hole
    (3) Asteroid belt 
    (4) White hole
    Answer:
    568. (4) A White Hole is a hypothetical hole in outer space from which energy, stars, and other celestial matter emerge or explode. It is a theoretical celestial object into which matter is funneled from a black hole.

    569. Light scattering takes place in

    (1) Colloidal solutions
    (2) Acidic solutions
    (3) Electrolyte solutions
    (4) Basic solutions
    Answer:
    569. (1) Light scattering in colloidal solutions or particles in suspension is known as Tyndall Effect. It is similar to Rayleigh scattering, in that the intensity of the scattered light depends on the fourth power of the frequency, so blue light is scattered much more strongly than red light.

    570. The term reactor referred to in waste water treatment is

    (1) Vessel 
    (2) Settling tank
    (3) Clarifier 
    (4) Aeration tank
    Answer:
    570. (4) Reactors are industrial processing tanks for the treatment of wastewater. The tanks have a “flow through” system, with raw wastewater (influent) coming in at one end and treated water (effluent) flowing out the other. While one tank is in settle/ decant mode the other is aerating and filling.

    571. A good conductor while carrying current is

    (1) alternately charged positive and negative
    (2) negatively charged
    (3) positively charged
    (4) electrically neutral
    Answer:
    571. (2) Electrons carry current in a good conductor of electricity and they are negatively charged. This makes a good electrical conductor negatively charged.

    572. The device used for measuring the wavelength of X-rays is

    (1) G.M. Counter
    (2) Cyclotron
    (3) Bragg Spectrometer
    (4) Mass Spectrometer
    Answer:
    572. (3) Bragg Spectrometer is an instrument used to analyze crystal structure by using X-rays. In it, a beam of collimated X-rays strikes the crystal, and a detector measures the angles and intensities of the reflected beam.

    573. Alpha particle is the nucleus of an atom of

    (1) Lithium 
    (2) Hydrogen
    (3) Helium 
    (4) Oxygen
    Answer:
    573. (3) Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus, which is generally produced in the process of alpha decay.

    574. Which of the following supports particle nature of photons ?

    (1) Diffraction 
    (2) Polarization
    (3) Photoelectric effect
    (4) Interference
    Answer:
    574. (3) Light is made up of photons, so it has some particle properties. In the photoelectric effect, light hits some material which absorbs it, and then ejects incident electrons. The reason that the photoelectric effect is evidence for the particle nature of light has to do with how materials absorb that light energy and then eject it in the form of electrons.

    575. Indicate the correct arrangement for electromagnetic radiation in order of their increasing wavelength.

    (1) Microwave, infrared, visible. X-rays
    (2) X -rays, visible, infrared, microwave
    (3) Visible, infrared, microwave, X-rays
    (4) X - rays, infrared, visible, microwave.
    Answer:
    575. (4) The Electromagnetic spectrum in order of decreasing energy, thus increasing wavelength : Gamma Rays– wavelength: 0.01 nm ; X-rays –1 nm ; Ultra-violet Rays-0.1 micrometres ; Visible LightRed light : 0.7 micrometres, Violet Light : 0.4 micrometres ; Infrared Radiation–0.01 mm ; Microwaves -less than 10 cm, usually 1cm ; Radiowaves- Long, Medium and Short Waves : 2 km-10 m ; and Very High Frequency (VHF) and Ultra High Frequency (UHF): 10 m–10 cm.

    576. Instrument used to study the behaviour of a vibrating string is :

    (1) Barometer 
    (2) Hydrometer
    (3) Hygrometer 
    (4) Sonometer
    Answer:
    576. (4) A Sonometer is a device for demonstrating the relationship between the frequency of the sound
    produced by a plucked string, and the tension, length and mass per unit length of the string. These
    relationships are usually called Mersenne's laws after Marin Mersenne (1588-1648), who investigated and codified them.

    577. What is a neuron ?

    (1) Basic unit of energy
    (2) Particle released during radioactivity
    (3) The anti-particle of neutron
    (4) Basic unit of nervous system
    Answer:
    577. (4) A neuron is a nerve cell that is the basic building block of the nervous system. Neurons are specialized to transmit infor-mation throughout the body. These highly specialized nerve cells are responsible for communicating information in both chemical and electrical forms.

    578. Which of the following is not caused by atmospheric refraction of light ?

    (1) Sun appearing red at sunset
    (2) Twinkling of stars at night
    (3) Sun appearing higher in the sky than it actually is
    (4) Sun becoming visible two or three minutes before actual sunrise
    Answer:
    578. (3) The twinkling of stars and variation in size of the Sun are due to atmospheric refraction of light. Besides, refraction is also responsible for the sun to look during sunset and sunrise. It is also responsible for the sun becoming two or three minutes before actual sunrise. The sun appears higher or lower in the sky due to the changing position of the Earth relative to the Sun.

    579. Matter waves are

    (1) de Broglie waves
    (2) Electromagnetic waves
    (3) Transverse waves
    (4) Longitudinal waves
    Answer:
    579. (1) In mechanics, matter waves or de Broglie waves reflects the wave–particle duality of matter. The de Broglie relations show that the wavelength is inversely proportional to the momentum of a particle and is also called de Broglie wavelength.

    580. When the milk is churned vigorously the cream from it is separated out due to

    (3) Centripetal force
    (2) Gravitational force
    (3) Frictional force
    (4) Centrifugal force
    Answer:
    580. (4) The separation of cream from milk is based on the fact that when liquids of different specific gravity revolve around the same centre at the same distance with the same velocity, a greater centrifugal force is exerted on the heavier liquid than on the lighter one. Milk consists of two liquids of different specific gravity: fat and milk serum.

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