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Term 1 Model Question Paper

12th Standard

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Physics

Time : 02:00:00 Hrs
Total Marks : 60
    6 x 1 = 6
  1. 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

  2. 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

  3. 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

  4. A non-conducting charged ring carrying a charge of q, mass m and radius r is rotated about its axis with constant angular speed ω. Find the ratio of its magnetic moment with angular momentum is _____.

    (a)

    \(\\ \frac { q }{ m } \)

    (b)

    \(\\ \frac { 2q }{ m } \)

    (c)

    \(\\ \frac { q }{ 2m } \)

    (d)

    \(\\ \frac { q }{ 4m } \)

  5. 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

  6. Which of the following is false for electromagnetic waves

    (a)

    transverse

    (b)

    non-mechanical waves

    (c)

    longitudinal

    (d)

    produced by accelerating charges

  7. 5 x 1 = 5
  8. Air

  9. (1)

    1 x 10-1m to 1 x 104m

  10. Electric Fuses

  11. (2)

    Lead

  12. RLC circuit

  13. (3)

    ε= 1

  14. Radio waves

  15. (4)

    Solar spectrum

  16. Fraunhofer Lines

  17. (5)

    Predominantly Inductive

    3 x 2 = 6
  18. Assertion: Two surfaces of spheres A and B of radii r1 and r2 when connected by a wire, form an equipotential surface. i.e VA= VB
    Reason: Surface charge density (σ) is inversely proportional to the radius of the sphere i.e sx\(\frac{1}{r}\). [as radius is smaller, σ will be larger]
    Codes:
    (a) Assertion and Reason are correct and Reason is the correct explanation of Assertion.
    (b) Assertion and Reason are true but Reason is the false explanation of the Assertion.
    (c) Assertion is true but Reason is false.
    (d) Assertion is false but Reason is true.

  19. Assertion: Kirchoff's voltage rule can be expressed as \({ \varepsilon }_{ 1 }+{ \varepsilon }_{ 2 }+{ \varepsilon }_{ 3 }+...{ \varepsilon }_{ n }={ I }_{ 1 }{ R }_{ 1 }+{ I }_{ 2 }{ R }_{ 2 }+...{ I }_{ n }{ R }_{ n }\)
    Reason: For the given diagrams

    Codes:
    (a) Assertion and Reason are correct and Reason is the correct explanation of Assertion.
    (b) Assertion and Reason are true but Reason is the false explanation of the Assertion.
    (c) Assertion is true but Reason is False.
    (d) Assertion is false but Reason is True

  20. Assertion: If two ends of a solenoid are bent and together to form a closed ring shape, it is called as toroid
    Reason: Magnetic field due to a long current-carrying solenoid is m
    B=\(\frac { \mu NI }{ L } \) =μnI (where, n=\(\frac { N }{ L } \))
    Codes:
    (a) Assertion and Reason are correct and Reason is the correct explanation of Assertion.
    (b) Assertion and Reason are true but Reason is the false explanation of the Assertion.
    (c) Assertion is true but Reason is false.
    (d) Assertion is false but Reason is true

  21. 5 x 2 = 10
  22. Define ‘electric dipole’. Give the expression for the magnitiude of its electric dipole moment and the direction.

  23. State microscopic form of Ohm’s law.

  24. Define magnetic flux.

  25. State Lenz’s law.

  26. What is meant by Fraunhofer lines?

  27. 6 x 3 = 18
  28. A block of mass m carrying a positive charge q is placed on an insulated frictionless inclined plane as shown in the figure. A uniform electric field E is applied parallel to the inclined surface such that the block is at rest. Calculate the magnitude of the electric field E.

  29. Obtain Gauss law from Coulomb’s law.

  30. A potential difference across 24 Ω resistor is 12 V. What is the current through the resistor?

  31. State and explain Kirchhoff ’s rules

  32. What is tangent law? Discuss in detail.

  33. How will you define the unit of inductance?

  34. 3 x 5 = 15
  35. A parallel plate capacitor has square plates of side 5 cm and separated by a distance of 1 mm.
    (a) Calculate the capacitance of this capacitor.
    (b) If a 10 V battery is connected to the capacitor, what is the charge stored in any one of the plates? (The value of εo = 8.85 x 10-12 Nm2 C-2)

  36. Two electric bulbs marked 20 W – 220 V and 100 W – 220 V are connected in series to 440 V supply. Which bulb will get fused?

  37. What is the value of x when the Wheatstone’s network is balanced?
    P = 500 Ω, Q = 800 Ω, R = x + 400, S = 1000 Ω

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