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SMT SULOCHANADEVI SINGHANIA SCHOOL,THANE CLASS 10 EXAM SUBJECT MARKS PRELIMINARY PHYSICS 80 TIME 2 hours PAGES 5 DATE 22.01.21 This paper has two sections of 40 marks each. Section I has 4 compulsory questions. Section II has 6 questions. Attempt any 4 questions. SECTION I (40 MARKS) Each question carries 2 x 5 = 10 marks. Q1. a) A couple is always needed to produce a rotation. Justify the statement with the example of opening a door. b) State the conditions required for equilibrium. c) Draw a graph showing the variation of angle of deviation with angle of incidence for refraction of light through a glass prism. d) Explain why stringed musical instruments are provided with a hollow box. e) Compare the MA of a single fixed pulley to MA of a single movable pulley. State an advantage of a single fixed pulley over a single movable pulley. Q2. a) What is the energy conversion ini) microphone ii) photosynthesis b) Is it possible to have accelerated motion with constant speed? Explain. c) Calculate the power of an engine required to lift 50000 kg of coal per hour from a mine 360m deep. (g = 10 m s-2) d) A parallel air slab is trapped in a glass block. A ray of light is incident from glass into the air slab at an angle = 60 degree from the surface. Draw a ray diagram showing the path of this ray as it emerges out from air to glass. 1 e) Define the SI unit of work. What is the relationship between SI and CGS unit of work? Q3. a) i) Why is white light considered to be polychromatic? ii) Give the range of wavelength of electromagnetic waves which are visible to us. b) It is possible to burn a piece of paper using a lens in daylight without using matches. How? c) The apparent height of a tree is 20m when viewed by a diver inside a pond. The real height of the tree is 15m. Find the refractive index of pond water. d) Ultrasonic waves are used in SONAR. Why? e) Identify the EM radiationi) Used for analysis of atomic and molecular structure. ii) The electric arc and sparks are source of this radiation. Q4. a) The effective resistance between A and B is 1.5 in the following circuit diagram. Find the value of resistor x. b) An iron ball requires 5000 J heat energy to raise its temperature by 10 C. Calculate the heat capacity of iron ball. If its mass is 1.1kg find its specific heat capacity. c) Differentiate between Potential energy and Kinetic energy. (2 points) 2 d) Find x and y in the following nuclear reaction. e) Wine and juice bottles are stored under water in cold places. Why? SECTION II Attempt any 4 questions. Each question carries 3+3+4 = 10 marks. Q5. a) A weight lifting champion lifted 261kg to a height of 2m in 4 s. Find i) the weight lifted by him. ii) work done by him and iii) the power developed by him. (g = 10 m s-2). b) Can the C.G. of a body be outside it? Explain with an example. Also use a diagram. c) Draw a labelled diagram of a block and tackle system of pulleys with 2 pulleys in each block. Write the relation between load and effort of this system. Q6.a) Draw a ray diagram to show the appearance of a coin placed underwater when viewed from above. b) Complete the path of the monochromatic ray PQ through a glass prism ABC. 3 c) An object is placed at a distance of 10cm in front of a concave lens of focal length 10cm. Find i) position of image ii) magnification iii) nature of the image. Q7. a) A uniform half metre rule rests horizontally on a knife edge at the 30cm mark when a mass of 10g is suspended from one end. Draw a diagram of the arrangement. What is the mass of the rule? b) What are damped vibrations? Draw a displacement- time graph for the same. c) Give reasonsi) When a troop crosses a suspension bridge, the soldiers are asked to break their steps. ii) The sound produced changes as a bucket is filling up with water. Q8.a) What is a beta particle? How is it emitted from a nucleus? What changes does it cause to the nucleus? b) Two resistors R1and R2 are put in series and then in parallel respectively. Identify the line corresponding to series combination in the following graph. Justify your choice. c) A battery of emf 8V and internal resistance 0.4 is connected to an ammeter of negligible resistance, a 1.6 resistor and an unknown resistor R1 connected in series. The reading in the ammeter is 2A. Draw a circuit diagram of the arrangement. Calculate R1 and the potential difference across it. 4 Q9. a) i) Icebergs can be carried by ocean currents over long distances without melting. Explain. ii) Name the material used to make a calorimeter. b) Study the graph below of the change of phases of a substance on heating at a constant rate and answer the following questions. i) Why is DE longer than BC? Ii) What is the state of the substance in the part CD? iii) What is the melting point of the substance? c) A brass rod of 0.2kg mass at 100 C is dropped into 0.5kg of water at 20 C. The final temperature of the mixture is 23 C. Find the specific heat capacity of brass. Q10.a) What is an electric fuse? Where is it connected? Give reason. b) Draw a diagram to show the deflection of radioactive radiations subjected to a magnetic field inwards of the paper. c) i) A nucleus 238P88 emits an alpha particle to form a nucleus Q which further disintegrates to form R by emitting gamma radiation and a beta particle. Write the complete nuclear reaction. ii) A mass of lead is embedded in a block of wood. Radiations from a radioactive source incident on the side of the block produces a shadow on a fluorescent screen placed beyond the block. The shadow of wood is faint but the shadow of lead is dark. Give reason for the difference. 5
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