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12th Standard English Medium Physics Reduced syllabus One mark important Questions - 2021(Public Exam )

12th Standard

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Physics

Time : 01:00:00 Hrs
Total Marks : 50

    Multiple Choice Questions

    50 x 1 = 50
  1. Two identical point charges of magnitude –q are fi xed as shown in the fi gure below. A third charge +q is placed midway between the two charges at the point P. Suppose this charge +q is displaced a small distance from the point P in the directions indicated by the arrows, in which direction(s) will +q be stable with respect to the displacement

    (a)

    A1 and A2

    (b)

    B1 and B2

    (c)

    both directions

    (d)

    No stable

  2. An electric dipole is placed at an alignment angle of 300 with an electric fi eld of 2 × 105 NC-1. It experiences a torque equal to 8 N m. Th e charge on the dipole if the dipole length is 1 cm is

    (a)

    4 mC

    (b)

    8 mC

    (c)

    5 mC

    (d)

    7 mC

  3. Four Gaussian surfaces are given below with charges inside each Gaussian surface. Rank the electric fl ux through each Gaussian surface in increasing order.

    (a)

    D < C < B < A

    (b)

    A < B = C < D

    (c)

    C < A = B < D

    (d)

    D > C > B > A

  4. Rank the electrostatic potential energies for the given system of charges in increasing order.

    (a)

    1 = 4 < 2 < 3

    (b)

    2 = 4 < 3 < 1

    (c)

    2 = 3 < 1 < 4

    (d)

    3 < 1 < 2 < 4

  5. If voltage applied on a capacitor is increased from V to 2V, choose the correct conclusion

    (a)

    Q remains the same, C is doubled

    (b)

    Q is doubled, C doubled

    (c)

    C remains same, Q doubled

    (d)

    Both Q and C remain same

  6. A parallel plate capacitor stores a charge Q at a voltage V. Suppose the area of the parallel plate capacitor and the distance between the plates are each doubled then which is the quantity that will change?

    (a)

    Capacitance

    (b)

    Charge

    (c)

    Voltage

    (d)

    Energy density

  7. The force experienced by a unit charge is called

    (a)

    Electric potential

    (b)

    Electric flux

    (c)

    Electric field

    (d)

    Static electricity

  8. A condenser is charged to a potential of 200V and has a charge of 0.1C. The energy stored in it is

    (a)

    1 J

    (b)

    2 J

    (c)

    10 J

    (d)

    20 J

  9. Increasing the charge on the plates of a capacitor means

    (a)

    increasing the capacitance

    (b)

    increasing the potential difference between the plates

    (c)

    both (a) and (b) above

    (d)

    none of the above

  10. A non-conducting material which has no free electrons is called

    (a)

    capacitor

    (b)

    Dielectric

    (c)

    conductor

    (d)

    Inductor

  11. When 4V emf is applied across a 1F capacitor, it will store energy of

    (a)

    2J

    (b)

    4J

    (c)

    6J

    (d)

    8J

  12. Value of k in Coulomb's law depends upon

    (a)

    magnitude of charges

    (b)

    distance between charges

    (c)

    both (a) and (b)

    (d)

    medium between two charges

  13. A charge Q is placed at the corner of a cube. The electric flux through all the six faces of the cube is

    (a)

    \(\frac { Q }{ { 3\varepsilon }_{ 0 } } \)

    (b)

    \(\frac { Q }{ { 6\varepsilon }_{ 0 } } \)

    (c)

    \(\frac { Q }{ { 8\varepsilon }_{ 0 } } \)

    (d)

    \(\frac { Q }{ { \varepsilon }_{ 0 } } \)

  14. A wire of resistance 2 ohms per meter is bent to form a circle of radius 1m. Th e equivalent resistance between its two diametrically opposite points, A and B as shown in the fi gure is

    (a)

    \(\pi \Omega\)

    (b)

    \(\frac{\pi}{2}\Omega\)

    (c)

    2\(\pi \Omega\)​​​​​​​

    (d)

    \(\frac{\pi}{4}\Omega\)

  15. A wire connected to a power supply of 230 V has power dissipation P1. Suppose the wire is cut into two equal pieces and connected parallel to the same power supply. In this case power dissipation is P2. The ratio \(\frac{P_2}{P_1}\) is

    (a)

    1

    (b)

    2

    (c)

    3

    (d)

    4

  16. In India electricity is supplied for domestic use at 220 V. It is supplied at 110 V in USA. If the resistance of a 60W bulb for use in India is R, the resistance of a 60W bulb for use in USA will be

    (a)

    R

    (b)

    2R

    (c)

    \(\frac{R}{4}\)

    (d)

    \(\frac{R}{2}\)

  17. Emission of electrons by the absorption of heat energy is called_______emission.

    (a)

    photoelectric

    (b)

    field

    (c)

    thermionic

    (d)

    secondary

  18. Find the energy released when 5.5 g of matter is used.

    (a)

    1.6 x 108 J

    (b)

    49.5 x 1015 J

    (c)

    49.5 x 1015 J

    (d)

    1.6 x 1019J

  19. mirror of focal length of f and the maximum and minimum distance of

    (a)

    1

    (b)

    2

    (c)

    3

    (d)

    4

  20. Millikan's oil drop experiment established that

    (a)

    electric charge depends on velocity

    (b)

    electric charge is quantised

    (c)

    electron has wave nature

    (d)

    electron has particle nature

  21. A beam of electron posses undeflected through mutually perpendicular electric and magnetic fields. If the electric field is switched off and the same magnetic field is maintained, the electrons move,

    (a)

    in a circular orbit

    (b)

    along a parabolic path

    (c)

    along a straight line

    (d)

    in an elliptical orbit

  22. When an electric field is applied to an atom each of the spectral lines split into several lines. This effect is known as

    (a)

    Zeeman effect

    (b)

    Stark effect

    (c)

    Raman effect

    (d)

    Seebeck effect

  23. J.J. Thomson discovered ________

    (a)

    protons

    (b)

    neutrons

    (c)

    electrons

    (d)

    quarks

  24. A spray of fine droplets of a highly viscous liquid could be, accomplished by a _________

    (a)

    filter

    (b)

    sieve

    (c)

    atomizer

    (d)

    mixer

  25. When the electron jumps from any of the outer orbits to the first orbit, spectral lines are emitted in the ________ region.

    (a)

    visible

    (b)

    IR

    (c)

    X-ray

    (d)

    UV

  26. In gamma ray emission from nucle

    (a)

    both the neutron number and the proton number change

    (b)

    there is no change in neutron number and the proton number change

    (c)

    only the neutron number changes

    (d)

    only the proton number changes

  27. In the nuclear reaction 4Be9+ X ➝ 6C12+ 0n1 X stands for

    (a)

    proton

    (b)

    α particle

    (c)

    electron

    (d)

    deutron

  28. Minimum size of a system in which at least 1 neutron is available for further fission is called __________

    (a)

    cut-off size

    (b)

    critical size

    (c)

    range of reactor

    (d)

    capability criteria

  29. The moderator used in nuclear reactor is

    (a)

    Cadmium

    (b)

    Boron oxide

    (c)

    Heavy water

    (d)

    Uranium

  30. The blue print for making ultra durable synthetic material is mimicked from

    (a)

    Lotus leaf

    (b)

    Morpho butterfly

    (c)

    Parrot fish

    (d)

    Peacock feather

  31. The method of making nanomaterial by assembling the atoms is called

    (a)

    Top down approach

    (b)

    Bottom up approach

    (c)

    Cross down approach

    (d)

    Diagonal approach

  32. Best example for applications. of nano technology

    (a)

    Chemical industry

    (b)

    Engineering

    (c)

    medicine

    (d)

    all of these

  33. One of the of Young’s double slits is covered with a glass plate as shown in figure. The position of central maximum will,

    (a)

    get shifted downwards

    (b)

    get shifted upwards

    (c)

    will remain the same

    (d)

    data insufficient to conclude

  34. A rear mirror of a vehicle is cylindrical having radius of curvature 10 cm. The length of arc of curved surface is also 10 cm. If the eye of driver is assumed to be at large distance, from the mirror, then the field of view in radian is

    (a)

    0.5

    (b)

    1

    (c)

    2

    (d)

    4

  35. The variation of frequency of carrier wave with respect to the amplitude of the modulating signal is called _______.

    (a)

    Amplitude modulation

    (b)

    Frequency modulation

    (c)

    Phase modulation

    (d)

    Pulse width modulation

  36. The Ac current gain of a transistor is 100. If the base current changes by 100 μA. What is the charge in collector current.

    (a)

    20 mA

    (b)

    30 mA

    (c)

    10 mA

    (d)

    10 μA

  37. The input resistance is ________

    (a)

    1k Ω

    (b)

    10 Ω

    (c)

    10 k Ω

    (d)

    100 Ω

  38. In frequency modulation

    (a)

    the amplitude of modulated wave varies as frequency

    (b)

    the frequency of modulated wave varies as amplitute the frequency

    (c)

    the amplitude of modulated wave varies as amplitute of carrier wave

    (d)

    the frequency of modulated wave varies as frequency of modulating wave

  39. Broadcasting antennas are generally

    (a)

    unidirectional

    (b)

    vertical

    (c)

    horizontal

    (d)

    none

  40. Long distance radio communication employs _______ wave propagation.

    (a)

    ground

    (b)

    sky

    (c)

    space

    (d)

    surface

  41. Low efficiency and small operating range are features of _________ type of transmission.

    (a)

    PM

    (b)

    AM

    (c)

    PCM

    (d)

    FM

  42. The centre of frequency is extremely stable in ___________ modulated wave.

    (a)

    amplitude

    (b)

    frequency

    (c)

    phase

    (d)

    pulse-code

  43. The speaker converts ________ energy into ______ energy.

    (a)

    electrical, sound

    (b)

    sound, electrical

    (c)

    light, sound

    (d)

    sound, mechanica

  44. Ihe circuit in which an inductor and a capacitor are connected in parallel is called as a _________

    (a)

    tank

    (b)

    series

    (c)

    inductor

    (d)

    capacitor

  45. ________ wire is used between telephones and the central office

    (a)

    Flat

    (b)

    Multiconnector

    (c)

    Co-axial

    (d)

    Twisted pair

  46. The distance of a geostationary satellite's orbit from the Earth is about _______

    (a)

    366 km

    (b)

    108 km

    (c)

    36 X 103km

    (d)

    30 m

  47. Supplier of majority charge carriers in a transistor is ______

    (a)

    emitter

    (b)

    base

    (c)

    collector

    (d)

    resistor

  48. Acceptor of majority charge carriers in a transistor is ___________

    (a)

    emitter

    (b)

    base

    (c)

    collector

    (d)

    resistor.

  49. lnput characteristics of an NPN transistor in (CE mode) is drawn between ________

    (a)

    IB and VBE

    (b)

    VBE and VCE

    (c)

    VCC andVEE

    (d)

    VB and IE

  50. Qutput characteristics of an NPN, transistor in CE mode is drawn between ___________

    (a)

    IC and VBE

    (b)

    IE and VCE

    (c)

    IB and VCE

    (d)

    IC and VCE

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