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CLASS X PHYSICS FIRST TERMINAL EXAMINATION Full Marks - 80 Time 2 Hr. SECTION I (40 MARKS) Attempt all questions in this section. 1. (a).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] (b) State the principle of conservation of energy. [2] (c) State the S.I. unit of the momentum of a body and Intensity of light. [2] (d)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] (e) 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] 2. (a). (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? (ii) Complete the ray diagram showing its emergence into air after passing through the prism. [2] [2] (b) An erect, diminished and virtual image is formed when an object is placed between the optical centre and principal focus of a lens. i. Name the type of lens, which forms the above image. [1] ii. Draw a ray diagram to show the formation of the image with the above characteristics. [3] (c) Why does the temperature of the surroundings start falling when the ice of a frozen lake starts melting? [2] 3. (a) Four resistances of 2.0 each are joined end to end to form a square ABCD. Calculate the equivalent resistance of the combination between any two adjacent corners. (b). In a three-pin plug, why is the earth pin made longer and thicker than the other two pins? (c) 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? (d). (i) State the law of conservation of energy. (ii) Name the chief energy transformation that occurs 1. in a Loudspeaker; 2. in an Electrical cell (Primary). 4. (a) State two application of an echo. (b) How does the resistance of a wire depend on its radius? Explain your answer. (c) Why is a fuse placed in a circuit is the thinnest or has the least cross section? (d) State Snell s law of refraction. (e) State the factors on which the deviation produced by a prism depends. [2] [2] [2] [4] [2] [2] [2] [2] [2] SECTION II (40 MARKS) Answer any 4 (four) questions in this section. 5. (a) What do you understand by the conservation of mechanical energy. [3] (b) Name a machine which is used to : (i) multiply force, (ii) multiply speed, and (iii) change the direction of force applied. [3] (c) A block and tackle system has the velocity ratio 3. A man can exert a pull of 200 kgf. What is the maximum load he can raise with this pulley system if its efficiency is 60%? [4] 6. (a) What is a prism? With the help of a diagram of a prism, indicate its refracting surfaces, refracting edge and base. [3] (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). 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. Find: (i) the heat lost by steam in terms of m1 (ii) the heat gained by ice in terms of m2. (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). [4]
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