ICSE 2009 Solved Important Papers of Physics By Mr. Saumendu Muherjee

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Physics

Q. 1.

(a). (i) A machine raises a load of 750 N through a height of 16 m in 5 seconds. Calculate the power at which the machine works. [2]

(ii) State the principle of conservation of energy. [2]

(b). (i) A cook uses a 'fire tong' of length 28 cm to lift a piece of burning coal of mass 250 g. If he applies his effort at a distance of 7 cm from the fulcrum, what is the effort in S.I. unit? Take g = 10 m/s². [3]

(ii) State the S.I. unit of the momentum of a body. [1]

(c). (i)The work done by the heart is 1 Joule per beat. Calculate the power of the heart if it beats 72 times in one minute. [2]

(ii) Mention two properties of a wave: one property which varies and the other which remains constant when the wave passes from one medium to another.[2]

(d). (i) In the diagram given below, a ray of light PQ is incident normally on one face AB of an equilateral glass prism. What are the angles of incidence at the faces AB and AC? [2]

(ii) Complete the ray diagram showing its emergence into air after passing through the prism. [2]

(e) An erect, diminished and virtual image is formed when an object is placed between the optical centre and principal focus of a lens.

1. Name the type of lens, which forms the above image. [1]
2. Draw a ray diagram to show the formation of the image with the above characteristics. [3]

(f) (i) Two friends were playing on their identical guitars whose strings were adjusted to give notes of the same pitch. Will the quality of the two notes be the same? Give a reason for your answer.

(ii) Give the relation wavelength, time-period and wave-velocity of a wave. [4]

(g) (i)Why does the temperature of the surroundings start falling when the ice of a frozen lake starts melting? [2]

(ii) Four resistances of 2.0Ω each are joined end to end to form a square ABCD. Calculate the equivalent resistance of the combination between any two adjacent corners. [2]

(h). (i) In a three-pin plug, why is the earth pin made longer and thicker than the other two pins? [2]

(ii)What is meant by the statement, 'the critical angle of diamond is 24° '?

How is the critical angle of a material related to its refractive index? [2]

(i). (i) State the law of conservation of energy. [4]

(ii) Name the chief energy transformation that occurs

1. in a Loudspeaker;
2. in an Electrical cell (Primary).

(j). (i) The diagram shows a point source of light S, a convex lens L and a plane mirror M. These are placed such that rays of light, from S return to it after reflection from M.

1. What is the distance OS called? [2]
2. To which point (left of S, on S, or right of S) will the rays return, if M is moved to the left and brought in contact with L?

(ii) Copy the diagram of the forearm given below, indicate positions of Load, Effort and Fulcrum. [2]

Section-B
(attempt any four)

Q. 2.

(a) Define: (i) Work (ii) Power and (iii) Energy. [3]

(b) How is work done related to the applied force? [1]

(c) By what factor does the kinetic energy of a moving body change when its speed is reduced to half? [1]

(d) What do the following units measure?

1. Pascal
2. Kilowatt hour. [2]

(e) From the ground floor, a man comes up to the fourth floor of a building using the staircase. Another person comes up to the same floor using an elevator. Neglecting friction, compare the work done in the two cases. [3]

Q. 3.

(i) Define specific heat capacity of a substance. State its S.I. unit. [3]

(ii) Give one example each where high specific heat capacity of water is used:

1. In cooling
2. As heat reservoir. [2]

(b) A vessel of negligible heat capacity contains 40 g of ice in it at 0°C. 8 g of steam at 100°C is passed into the ice to melt it. Find the final temperature of the contents of the vessel.
(Specific latent heat of vaporization of steam, = 2268 J/g; Specific latent heat of fusion of ice = 336 J/g and Specific heat capacity of water = 4.2 J/g°C) [5]

1. Draw a ray diagram to illustrate the action of a convergent lens as a reading lens or a magnifying glass.
2. A prism deviates a monochromatic ray of light through an angle 'δ' when the angle of incidence at the surface of the prism is 'i'.

1. Draw a graph showing the variation of 'δ' with 'i'. On Your graph show the angle of minimum deviation. [2]
2. What is the relation between the angle of incidence and the angle of emergence when the ray suffers minimum deviation. [1]

Q. 4.

(c). (i) Two isosceles right-angled prisms are arranged as shown in the figure. Copy the diagram and complete the path of the ray AB along which it passes through the prisms and comes out. [1]

(ii) Name the phenomenon being displayed by the path of the ray in the diagram. [2]

Q. 5.

(a) The rear view mirror of a motor bike starts vibrating violently at some particular speed of the motor bike. [4]

1. Why does this happen?
2. What is the name of the phenomenon taking place?
3. What could be done to stop the violent vibrations?

(b) A sound wave of wavelength 0.332 m has a time period of 10^-3 s. If the time period is decreased to 10^-4 s; calculate the wavelength and frequency of the new wave. [3]

(c) (i) Define the terms: Amplitude and frequency for sound waves. [3]

(ii) Name the subjective property of sound related to its frequency and of light related to its wavelength.

Question 6

(a). A radar is able to detect the reflected waves from an enemy aeroplane, after a time interval of 0.02 milliseconds. If the velocity of the waves is 3×10⁸ ms^-1, calculate the distance of the plane from the radar. [3]

(b). A piece of ice is heated at a constant rate. The variation of temperature with heat input is shown in the graph below: [4]

1. What are represented by AB and CD ?
2. What conclusion can you draw regarding the nature of ice from the alongside graph ?

(c). If there is no heat loss to the surroundings, the heat released by the condensation of m²g of ice at, 0°C into water at 0°C.

(i). Find:

1. the heat lost by steam in terms of m¹
2. the heat gained by ice in terms of m².

(ii). Form a heat equation and find the ratio of m² : m¹ from it.
(Specific latent heat of vaporization of steam = 2268 kJ/kg;
Specific latent heat of fusion of ice = 336 kJ/kg.
Specific heat capacity of water = 4200 J/kg°C).

Q. 7.

(a). An electrical appliance is rated 1500 W, 250 V. This appliance is connected to 250 V mains.

Calculate:

1. the current drawn,
2. the electrical energy consumed in 60 hours,
3. the cost of electrical energy consumed at Rs. 2.50 per KWH.

(b). A monochromatic point source of light 'O' is seen through a rectangular glass block ABCD. Paths of two rays, in and outside the block, are shown in the figure below. [4]

1. Does the source 'O' appear to be nearer or farther with respect to the surface AB?
2. How does the shift depend on the thickness (AD or BC) of the block?
3. Justify your answer in (ii) with the help of an appropriate ray diagram.
4. For the same rectangular glass block, which colour from the visible spectra will produce the maximum shift?
   

(c). In the figure given alongside, A, B and C are three ammeters. The ammeter B reads 0.5A. (All the ammeters have negligible resistance.) [3]

Calculate:

1. the readings in the ammeters A and C
2. the total resistance of the circuit.

Paper By Mr. Saumendu Mukherjee