ICSE-X-Physics

Previous Year Paper year:2019

with Solutions - page 7

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  • #8-c-i
    the resistance of the circuit when the key k is crpen.
    Ans : RS = 5 + 0.5 = 5.5 Ω
  • #8-c-ii
    the current drawn from the cell when the key k is open,
    Ans : I=``\frac { V }{ R }``=``\frac { 3.3 }{ 5.5 }``= 0.6A
  • #8-c-iii
    the resistance of the circuit when the key k is closed.
    Ans : RP = ``\frac{5 \times 5}{5+5}`` == 2.5 Ω, thus total resistance is RT = 2.5 +0.5 = 3.0


  • #8-c-iv
    the current drawn from the cell when the key k is closed.
    Ans : I= ``\frac{\mathrm{V}}{\mathrm{R}_{\mathrm{T}}}`` = ``\frac { 3.3 }{ 3.0 }``

    = 1.1 A


  • #9
  • #9-a
  • #9-a-i
    Define Calorimetry.
    Ans : Calorimetry is the measurement of heat,
  • #9-a-ii
    Name the material used for making a Calorimeter.
    Ans : Copper.
  • #9-a-iii
    Why is a Calorimeter made-up of thin sheets of the above material answered in (ii) ?

    [3]
    Ans : Copper has small specific heat capacity. The thin sheets ensure that the box has small heat capacity.


  • #9-b
    The melting point of naphthalene is 80°C and the room temperature is 30°C. A sample of

    liquid naphthalene at 100°C is cooled down to the room temperature. Draw a temperature¬time graph to represent this cooling. In the graph, mark the region which corresponds to the freezing process.

    [3]
    Ans : The graph is as shown :




  • #9-c
    104 g of water at 30°C is taken in a calorimeter made of copper of mass 42 g. When a certain mass of ice at 0°C is added to it, the final steady temperature of the mixture after the ice has melted, was found to be 10°C. Find the mass of ice added.

    [Specific heat capacity of water = 4.2 J g-1 °C-1 : Specific latent heat of fusion of ice - 336 J g-1 ; Specific heat capacity of copper = 0.4 J g-1 °C-1 ]

    [4]
    Ans : Mass of water m1 = 104 g

    Temperature of water T1 = 30°C

    Final temperature T2 = 10°C

    Mass of calorimeter m2 = 42 g

    Temperature of ice T3= 0°C

    Let the mass of ice added be = x g

    Total heat energy lost = ``(104 \times 4.2 \times 20)+(42 \times 0.4 \times 20) = 8736 + 336 = 9072 J``

    Total heat energy gained = ``(336 \times x)+(x \times 4.2 \times 10) = 336x + 42x = 378x``

    By principle of calorimetry,

    Heat lost = Heat gained

    378x =9072

    x = ``\frac { 9072 }{ 378 }`` = 24g


  • #10
  • #10-a
    Draw a neat labelled diagram of an AC generator.
    Ans : The diagram is as shown:




  • #10-b
  • #10-b-i
    Define nuclear fission.
    Ans : It is the splitting of a heavy nudeus into two or more smaller nudei with the

    release of tremendous energy.