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12th Standard Physics Revision Model Question Paper with Answer Key

12th Standard

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Physics

Time : 02:30:00 Hrs
Total Marks : 70

    PART - I

    Note : i ) All Questions Are Compulsory.

                 ii) Choose The Most Suitable Answer From The Given Four Correct Alternatives


    15 x 1 = 15
  1. Which charge configuration produces a uniform electric field?

    (a)

    point charge

    (b)

    uniformly charged infinite line

    (c)

    uniformly charged infinite plane

    (d)

    uniformly charged spherical shell

  2. An electric dipole is placed at an alignment angle of 30o with an electric field of 2 x 105 NC-1. It experiences a torque equal to 8 N m. The 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. A toaster operating at 240 V has a resistance of 120 Ω. The power is ______.

    (a)

    400 W

    (b)

    2 W

    (c)

    480 W

    (d)

    240 W

  4. A carbon resistor of (47 ± 4.7 ) k Ω to be marked with rings of different colours for its identification. The colour code sequence will be ______.

    (a)

    Yellow – Green – Violet – Gold

    (b)

    Yellow – Violet – Orange – Silver

    (c)

    Violet – Yellow – Orange – Silver

    (d)

    Green – Orange – Violet - Gold

  5. A circular coil of radius 5 cm and 50 turns carries a current of 3 ampere. The magnetic dipole moment of the coil is nearly ____.

    (a)

    1.0 A m2

    (b)

    1.2 A m2

    (c)

    0.5 A m2

    (d)

    0.8 A m2

  6. A thin insulated wire forms a plane spiral of N = 100 tight turns carrying a current I = 8 m A (milli ampere). The radii of inside and outside turns are a = 50 mm and b = 100 mm respectively. The magnetic induction at the centre of the spiral is ______.

    (a)

    \(5\mu T\)

    (b)

    \(7\mu T\)

    (c)

    \(8\mu T\)

    (d)

    \(10\mu T\)

  7. The flux linked with a coil at any instant t is given by \(\Phi\)B = 10t− 50t + 250. The induced emf at t = 3s is

    (a)

    −190 V

    (b)

    −10 V

    (c)

    10 V

    (d)

    190 V

  8. When the current changes from +2A to −2A in 0.05 s, an emf of 8 V is induced in a coil. The co-efficient of self-induction of the coil is

    (a)

    0.2H

    (b)

    0.4H

    (c)

    0.8H

    (d)

    0.1H

  9. The dimension of \(\frac { 1 }{ { \mu }_{ 0 }{ \varepsilon }_{ 0 } } \) is _____.

    (a)

    [LT-1]

    (b)

    [L2T-2]

    (c)

    [L-1T]

    (d)

    [L-2T2]

  10. The speed of light in an isotropic medium depends on, ______.

    (a)

    its intensity

    (b)

    its wavelength

    (c)

    the nature of propagation

    (d)

    the motion of the source w.r.t medium

  11. The wavelength λe of an electron and λp of a photon of same energy E are related by _____.

    (a)

    λp λe

    (b)

    \({ \lambda }_{ p }∝ \sqrt { { \lambda }_{ e } } \)

    (c)

    \({ \lambda }_{ p }∝ \frac { 1 }{ \sqrt { { \lambda }_{ e } } } \)

    (d)

    \({ \lambda }_{ p }∝ { \lambda }_{ e }^{ 2 }\)

  12. Suppose an alpha particle accelerated by a potential of V volt is allowed to collide with a nucleus of atomic number Z, then the distance of closest approach of alpha particle to the nucleus is _____.

    (a)

    \(14.4\frac { Z }{ V } \mathring { A } \)

    (b)

    \(14.4\frac { V }{ Z } \mathring { A } \)

    (c)

    \(1.44\frac { Z }{ V } \mathring { A } \)

    (d)

    \(1.44\frac { V }{ Z } \mathring { A } \)

  13. The particle size of ZnO material is 30 nm. Based on the dimension it is classified as _____.

    (a)

    Bulk material

    (b)

    Nanomaterial

    (c)

    Soft material

    (d)

    Magnetic material

  14. A plane glass is placed over a various coloured letters (violet, green, yellow, red) The letter which appears to be raised more is _____.

    (a)

    red

    (b)

    yellow

    (c)

    green

    (d)

    violet

  15. The barrier potential of a silicon diode is approximately, ______.

    (a)

    0.7 V

    (b)

    0.3 V

    (c)

    2.0 V

    (d)

    2.2 V

  16. PART - II


    Note : Answer Any Six Questions No. 24 is Compulsory


    6 x 2 = 12
  17. Why do metals have a large number of free electrons?

  18. What are cathode rays?

  19. Give any two examples for “Nano” in nature.

  20. What is angle of deviation due to refraction?

  21. The relative magnetic permeability of the medium is 2.5 and the relative electrical permittivity of the medium is 2.25. Compute the refractive index of the medium.

  22. A circular antenna of area 3 m2 is installed at a place in Madurai. The plane of the area of antenna is inclined at 47o with the direction of Earth’s magnetic field. If the magnitude of Earth’s field at that place is 4.1 x 10–5 T find the magnetic flux linked with the antenna.

  23. The horizontal component and vertical component of Earth’s magnetic field at a place are 0.15 G and 0.26 G respectively. Calculate the angle of dip and resultant magnetic field. (G - gauss, cgs unit for magnetic field 1G = 10–4 T)

  24. Why current is a scalar?

  25. Calculate the number of electrons in one coulomb of negative charge.

  26. PART - III

    Note : Answer Any Six Questions. Question No. 33 is Compulsory


    6 x 3 = 18
  27. Calculate the electrostatic force and gravitational force between the proton and the electron in a hydrogen atom. They are separated by a distance of 5.3 x 10–11 m. The magnitude of charges on the electron and proton are 1.6 x 10–19 C. Mass of the electron is me = 9.1 x 10–31 kg and mass of proton is mp = 1.6 x 10–27 kg.

  28. Distinguish between drift velocity and mobility.

  29. Consider a magnetic dipole which on switching ON external magnetic field orient only in two possible ways i.e., one along the direction of the magnetic field (parallel to the field) and another anti-parallel to magnetic field. Compute the energy for the possible orientation.

  30. A solenoid of 500 turns is wound on an iron core of relative permeability 800. The length and radius of the solenoid are 40 cm and 3 cm respectively. Calculate the average emf induced in the solenoid if the current in it changes from 0 to 3 A in 0.4 second.

  31. A pulse of light of duration 10−6 s is absorbed completely by a small object initially at rest. If the power of the pulse is 60\(\times\) 10−3 W. Calculate the final momentum of the object.

  32. What is optical path? Obtain the equation for optical path.

  33. List out the laws of photo electric effect.

  34. Write the properties of cathode rays.

  35. What is the difference between Nano materials and Bulk materials?

  36. PART - IV

    Note : Answer all the Questions 


    5 x 5 = 25
    1. Discuss the basic properties of electric charges.

    2. Describe the microscopic model of current and obtain general form of Ohm’s law.

    1. Discuss Earth’s magnetic field in detail.

    2. Give the uses of Foucault current.

    1. Discuss the Hertz experiment.

    2. Describe the Fizeau’s method to determine the speed of light.

    1. Briefly discuss the observations of Hertz, Hallwachs and Lenard.

    2. Derive the energy expression for an electron is the hydrogen atom using Bohr atom model.

    1. Discuss the applications of Nanomaterials in various fields.

    2. Prove law of refraction using Huygens’ principle.

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