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ICSE-X-Physics

Previous Year Paper year:2019

with Solutions - page 4

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  • #4-c
    A magnet kept at the centre of two coils A and B is moved to and fro as shouni in the diagram. The two galvanometers show deflection.



    State with a reason whether :

    x > y or x <y [x and y are magnitudes of deflection]

    [2]
    Ans : x < y. This is because coil B has more number of turns.


  • #4-d
  • #4-d-i
    Why is a nuclear fusion reaction called a thermo nuclear reaction?
    Ans : Because this occurs at a very high temperature.
  • #4-d-ii
    Complete the reaction :

    [2]

    3 He2 + 2H1→ 4He2 +.......+Energy
    Ans : 3He2 + 2H1 → 4He2 + 1H1 + Energy


  • #4-e
    State two ways to increase the speed of rotation of a DC motor.

    [2]
    Ans : The two ways are



    1. Strong magnet and
    2. High current.
    Section - II [40 Marks]

    (Attempt any four questions from this Section)


  • #5
  • #5-a
    A body of mass 10 kg is kept at a height of 5 m. It is allowed to fall and reach the ground.
  • #5-a-i
    What is the total mechanical energy possessed by the body at the height of 2 m assuming it is a frictionless medium?
    Ans : The total mechanical energy is the total potential energy it possesses before its fall.

    E = mgh = ``10 \times 10 \times 5 = 500 J``

    It is equal to the maximum potential energy E = mgh = ``10 \times 10 \times 5 = 500 J``.


  • #5-a-ii
    What is the kinetic energy possessed by the body just before hitting the ground? Take

    g= 10 m s-2.

    [3]
  • #5-b
    A uniform metre scale is in equilibrium as shown in the diagram :


  • #5-b-i
    Calculate the weight of the metre scale.
    Ans : The weight of the metre scale acts at its centre of gravity i.e., at 50 cm mark.

    By the concept of moments, we have

    ``40 \times (30 - 5 ) = W \times (50 - 30)``

    or ``W = \frac{(40 \times 25)}{20} = 50 gf``

    -(ii) F is shifted towards 0 cm.


  • #5-b-ii
    Which of the following options is correct to keep the ruler in equilibrium when 40 gf wt is shifted to 0 cm mark?

    F is shifted towards 0 cm or

    F is shifted towards 100 cm.

    [3]
  • #5-c
    The diagram below shows a pulley arrangement :


  • #5-c-i
    Copy the diagram and mark the direction of tension on each strand of the string.
    Ans : The direction of tension is as marked.

  • #5-c-ii
    What is the velocity ratio of the arrangement?
    Ans : VR = Distance travelled by effort/Distance travelled by load =
    ``\frac { 2x }{ 2 }`` = 2.

    The distance travelled by load is half the distance moved by effort = ``\frac { x }{ 2 }``
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