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NDA & NA (II) 2017 Exam: GK-Physics Practice Questions

Sep 7, 2017 15:52 IST
    NDA & NA (II) 2017 Exam: GK-Physics Practice Questions
    NDA & NA (II) 2017 Exam: GK-Physics Practice Questions

    For the benefit of NDA & NA (II) 2017 Exam aspirants, Jagran Josh is providing physics practice questions. The questions were prepared by taking into account the questions asked previously in NDA exams. The answers along with detailed explanations will help the aspirants in rectifying their mistakes in solving the question paper and help in scoring good marks in the final exam.

    1.  Cryogenic engines find applications in:

    (a) sub-marine propulsion

    (b)    frost-free refrigerators

    (c)    rocket technology

    (d)    researches in superconductivity

    2. The clouds float in the atmosphere because of low :

    (a) temperature

    (b) velocity

    (c) pressure

    (d) density

    3. Given below are two statements, one labelled as Assertion (A) and other labelled as Reason (R)

    Assertion (A): A diamond sparkles more than a glass imitation cut to the same shape.

    Reason (R): The refractive index of diamond is less than that of glass.

    In context of the above two statements, which one of the following is correct ?

    (a)    Both A and R are true and R is the correct explanation of A

    (b)    Both A and R are true and R is not a correct explanation of A

    (c)    A is true but R is false

    (d)    A is false but R is true

    4. An air bubble in water will act like a ;

    (a) convex mirror

    (b) convex lens

    (c) concave mirror

    (d) cancave lens

    5. When a mirror is rotated by an angle 0, the reflected ray will rotate by :

    (a) 0°

    (b) 0/2

    (c) 0

    (d) 20

    6. Total internal reflection can take place when light travels from :

    (a) diamond to glass

    (b) water to glass

    (c) air to water

    (d) air to glass

    7.  Given below are two statements, one labelled as Assertion (A) and the other labelled as Reason (R).

    Assertion (A) : Transformer is useful for stepping up or stepping down voltages.

    Reason (R) : Transformer is a device used in D.C. circuits.

    In the context of the above two statements, which one of the following is correct ?

    (a) Both A and R are true and R is the correct explanation of A

    (b) Both A and R are true but R is not a correct explanation of A

    (c) A is true but R is false

    (d) A is false but R is true

    8. When the frequency distribution is normal :

    (a) median, mode and mean are all different from one another

    (b) mean, mode and median are identical

    (c) mean is greater than mode

    (d) mean is greater than median

    9. Domestic electrical wiring is basically a :

    (a)    series connection

    (b)    parallel connection

    (c)    combination of series and parallel connections

    (d)    series connection within each room and parallel connection elsewhere

    10.        Consider the following statements :

    At the present level of technology available in India, solar energy can be conveniently used to

    1.    Supply hot water to residential buildings.

    2.    Supply water for minor irrigation projects.

    3.    Provide street lighting.

    4.    Electrify a cluster of villages and small towns.

    (a)    1, 2, 3 and 4 are correct

    (b)    2 and 4 are correct

    (c)    1 and 3 are correct

    (d)    1, 2 and 3 are correct

    11. Which of the following is the best electricity conductor?

    a)    Copper

    b)    Aluminium

    c)    Iron

    d)    Silver

    12. Identify the pair that is correctly matched?

    a)    Madam Curie: X – ray

    b)    Albert Einstein: Photoelectric effect

    c)    Linus Pauling: Electron

    d)    C V Raman: Stark effect

    13. Small liquid drops are spherical in shape because

    a)    of adhesion

    b)    of gravitational force

    c)    of the atmospheric pressure from all the sides on the top

    d)    the liquid tends to have the minimum surface area are due to surface tension

    14. The minimum possible temperature beyond which matter cannot be cooled is in degree Centigrades is

    a)    95.50

    b)    100

    c)    273.15

    d)    473.50

    15. The Chandershekhar Limit is related to which of the following?

    a)    Stars

    b)    Black holes

    c)    Both of these

    d)    None of these

    16. Who among the following is credited for discovering the principles underlying electromagnetic induction?

    a)    Michael Faraday

    b)    Volta

    c)    Coulomb

    d)    Gauss

    17. Refraction, Reflection, Dispersion and Diffraction are associated with

    a)    Light

    b)    Sound

    c)    Magnetism

    d)    None of the Above

    18. A Light Year is a measure of

    a)    Light intensity

    b)    Time

    c)    Distance

    d)    None of the Above

    19. It is on this principle, the quartz clock works.

    a)    Piezo-electric effect

    b)    Gauss effect

    c)    Relativistic effect

    d)    Mass defect

    20. In the Solar System, asteroids circle between these two planets.

    a)    Venus and Mars

    b)    Mars and Earth

    c)    Mars and Jupiter

    d)    Jupiter and Saturn

    Answers with Explanations

    1.(c) rocket technology

    Cryogenic engines find applications in rocket technology.

    2. (a) temperature   

    When air rises, it is cooled by expansion. After dew point has reached cooling leads to condensation of water vapour in the atmosphere. Tiny droplets of water vapour which are too small to fall as raize or shower will be suspended in the air and float as clouds.

    3. (c) A is true but R is false

    The refractive index of diamond is very high  (approximately 2.47) while the refractive index for  the glass is 1.57. Therefore, the initial angle for the ray of light traveling form diamond to air is very low about 24°. The initial angle for the ray of light traveling from glass to air is 39°. Moreover the diamonds are usually cut with their faces in such a manner that once a ray of light enters into it, it suffers a large number of total internal reflections at various faces till the angle of incidence inside the diamond remains greater than the critical angle. In total internal reflection 100% of the light reflected back into the same medium. Hence, the object shines. That's why a diamond sparkles more than a glass imitation cut to the same shape.

    4.(d) cancave lens

    5. (d) 20

    For given incident ray, if a plane mirror is rotated through a certain angle, then the reflected ray rotates through twice of that angle . So if a mirror is rotated by an angle 0, the reflected ray will rotate by 20.

    6. (a) diamond to glass

    Total internal reflection takes place when light travels from optically denser medium to optically rarer medium. (Refractive index for diamond = 2.45, refractive index for glass = 1.57)

    7. (c) A is true but R is false

    Assertion A is true but reason R is false. Because a transformer is a device that enables us to step up or step down a given A.C. voltage according to our requirement. A transformer can not work or can not be used with a direct current (D.C.) as it's working is based on the change of magnetic flux with a varying current. Thus, it works only when input is alternating.

    8.(b) mean, mode and median are identical

    When the frequency distribution is normal median, mode and mean are all identical

    9.(b) parallel connection

    Domestic electrical wiring is basically a' parallel connection. In parallel circuit each branch receives equal current. In parallel connection if one of the bulbs is removed from the circuit, i.e., if one of the branches in the circuit is broken, electric current will still flow in other branches and other bulbs will continue to glow.

    10. (c) 1 and 3 are correct

    At present level solar energy can be conveniently used to provide street lighting and supply hot water to residential buildings.

    11. (d) Silver

    Pure Silver is the best conductor of electricity, but since it is not so easily available, other alternatives are more popular. Electrical conductivity of a material is a function of how easily its atoms can provide free electrons to pass a current. Any material which does not have free electrons in its atoms, cannot conduct electricity.

    12. (b) Albert Einstein: Photoelectric effect

    In many languages, X-radiation is referred to with terms meaning Röntgen radiation, after the German scientist Wilhelm Röntgen, who usually is credited as its discoverer, and who had named it X-radiation to signify an unknown type of radiation. C V Raman is known for Raman Effect for which he won the Nobel Prize. Albert Einstein got the Nobel Physics Prize for this discovery of photo-electric equation. Madam Curie – Radioactivity. Linus Pauling – Electro negativity scale.

    13. (d) the liquid tends to have the minimum surface area are due to surface tension

    A drop of a liquid tries to occupy the minimum surface are in a given volume as it is constantly under  a kind of stretch among its molecules. This minimum area is achieved by assuming a spherical shape. These cohesive forces create surface tension which means that the upper surface of a liquid always shows tension.

    14. (c) - 273.15

    This temperature is also called the absolute zero of temperature. Absolute zero is the lower limit of thermodynamic temperature scale, a state in which the enthalpy and entropy of a cooled ideal gas is at its minimum value, taken as 0. All molecular motion is supposed to cease at this point, at least in theory.

    15. (a) Stars

    It refers to the mass limit of the stars, beyond which they collapse. The Chandrasekhar limit is the maximum mass of a stable, white dwarf star. It is the mass above which electron degeneracy pressure in the star is not enough to its own gravitational pull. Consequently, white dwarfs with masses greater than this limit would suffer gravitational collapse, evolving into a neutron star or black hole.

    16. (a) Michael Faraday

    Michael Faraday was an English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic induction, diamagnetism and electrolysis.

    17. (a) Light

    In optics, refraction is a phenomenon that often occurs when waves travel from a medium with a given refractive index to a medium with another at an oblique angle. Reflection of light is either specular (mirror-like) or diffuse (retaining the energy, but losing the image) depending on the nature of the interface. Dispersion is the separation of white light into colours or of any radiation according to wavelength. Diffraction is the slight bending of light as it passes around the edge of an object.

    18. (c) Distance

    A Light Year is known as the distance travelled by light in one year, which is equal to 3 lakh kilometer/sec × 24 hrs × 60 min × 60 seconds. This unit is used to measure astronomical distances between various celestial bodies like planets, stars, galaxies, etc.

    19. (a) Piezo-electric effect

    The principle of Piezoelectricity refers to the electrical charge, which accumulates in certain solids like crystals, ceramics, bone, DNA and various proteins in response to mechanical stress. The word piezoelectricity means electricity resulting from pressure.

    20. (c) Mars and Jupiter

    The asteroids are minor planets, especially those in the inner Solar System. The term was earlier  applied to any astronomical object orbiting the Sun, which did not show the disc of a planet and was did not have comet-like properties. But in modern science, the term "asteroid" refers to the minor planets of the inner Solar System including those which are co-orbital with Jupiter.

    NDA & NA (II) 2017 Exam: GK-General Science Practice Questions

    NDA & NA (II) 2017 Exam: English Mock Test

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