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BOMBAY SCOTTISH SCHOOL. MAHIM Preliminary Examination PHYSICS Standard : 10 Date : 14-01-2020 Max. Marks : 80 No. of Questions : 10 Answers to this paper must be written on the answer paper provided separately. You will not be allowed to write during the first 15 minutes. This time is to be spent in reading the question paper. The time mentioned above is the time allowed to write the answers. ------------------------------------------------------------------------------------------------------Section I is compulsory. Attempt any four questions from section II. The intended marks for questions or the parts of the question are given in bracket. -------------------------------------------------------------------------------------------------------- Section I [Compulsory] Question 1 a) The diagram below shows the pictures A and B are of nail cutters. Identify the class of each lever. [2] A B b) The diagram below shows a man walking ahead on a levelled road and the corresponding forces acting. From the diagram, name the force i) doing positive work. ii) doing zero work. [2] c) If critical angle of glass for yellow colour is 450, then critical angle of glass for blue colour can be 450 30 . State with a reason whether the above statement is true or false. [2] 1 d) A metal sphere of mass 200 g falls from a height of 5 m. Calculate the velocity with which it will strike the ground. [g = 10 ms-2] [2] e) A single fixed pulley applies 20 kgf force to lift a body weighing 18kgf. Calculate i) M.A. of the pulley system. ii) What will be its velocity ratio if the force of friction is doubled for the same pulley. [2] Question 2 a) The diagram below shows the relation between angle of deviation and angle of incidence when refraction takes place through an equilateral prism. Use this graph to find out the value of x. [2] b) Observe the diagram given below and answer the questions that follow 1. Name the lens 2. Name the distance OX [2] c) State the principle on which the optic fibre works and state one use of optic fibre. d) Why are the danger signal lights on the top of skyscrapers, red in colour? [2] [2] e) Complete the path of rays AB and AC till they emerge out of the rectangular glass prism. [2] Question 3 a) The diagram below shows a metre scale balanced at 30 cm mark. State which of the following option is true [2] i) Weight of the scale > 50 gf ii) Weight of the scale < 50gf iii) Weight of the metre scale = 50gf b) Name the vibrations executed by a pendulum in air when it is disturbed once from its mean position and define these vibrations. [2] 2 c) What is meant by sound ranging? State one use of sound ranging. [2] d) Calculate the resistance X if the total resistance across AB is 2.1 [2] e) Calculate the heat absorbed by 200 g ice present at 0 0C to raise its temperature to water at 100 0C. [Sp. Heat capacity of water = 4.2 jg-1 0C-1, Sp. Latent heat of ice = 336 jg-1] [2] Question 4 a) A given copper wire is stretched to double its length. What is the effect on its i) ii) Resistance? Resistivity? [2] b) State two differences between D.C. motor and A.C. generator. c) [2] What is the meaning of the statement Heat capacity of a metal piece is 67 JK-1 [2] d) Radioactive source emits three types of radiations 1. Name the radiation of zero mass 2. Name the radiation which has highest ionising power. e) [2] A nuclear radiation when passes through a magnetic field which is perpendicularly into the paper as shown below, deflects towards B. Identify the nuclear radiation. [2] Section II [Attempt any four questions from this section] Question 5 a) State i) ii) iii) the major energy conversion in the following A rotating fan A lead bullet fired from an air gun. A microphone used for speaking. [3] b) The graph shows the work done by a force against the displacement produced. [3] i) Calculate the force acting. ii) The displacement when the work done by the force is 200 j. c) A metal ball of mass m is released from height h i) Calculate the total mechanical energy when it is just released. ii) Calculate the total mechanical energy when it comes down vertically 3 through a certain distance x m and show that it remains the same [4] Question 6 a) [3] Redraw and complete the path of the ray AB till it emerges out of the glass prism of critical angle 420 b) The diagram below shows an object O is viewed through a triangular prism when seen from point X. O is the image seen. i) ii) c) i) ii) [3] Name the phenomenon involved. State the conditions needed for this phenomenon to take place. Draw a ray diagram showing the formation of magnified image when an object is kept within the focal length of this lens. If the focal length of this lens is 16 cm and the object is placed at a distance of 12 cm from the lens then calculate the image distance from the lens. [4] a) Certain electromagnetic radiations change the paper dipped in silver chloride solution, violet in colour. i) Identify the radiations. ii) State the material of the prism used to obtain these radiations. iii) State one important use of this radiation. [3] Question 7 b) A block and tackle system of velocity ratio 3 is used to raise a load of 120 kgf through a height of 2 m. If the efficiency of the pulley system is 80% then calculate i) ii) Effort needed. Displacement of the effort required. [3] c) Classify the following levers as force multiplier or speed multiplier. i) iv) Crow bar ii) bottle opener. Human forearm iii) Canoeing oar [4] Question 8 a) Three pendulums are tied to a flexible string tied between two rigid supports X and Y. Pendulum A is set into vibration. It is observed that B and C also starts vibrating and amplitude of vibration attained by pendulum B is smaller than that of C. i) Give reason for the above observations. 4 ii) State the relation between the length of the pendulum and its frequency of vibration. b) A solid X with specific heat capacity 0.8 jg-1 0C-1 is heated till it melts. i) State whether its specific heat capacity remains the same or changes on melting. 0.6 jg-1 0C-1, 0.25 jg-1 0C-1 and1.45 jg-1 0C-1 are specific heat capacities. If one of the above is the specific heat capacity of molten X then which one is the most probable? Give a reason for your answer. [3] c) A person standing between two vertical cliffs and 660 m away from the nearer cliff, fires a gun. He hears first echo after 4 s and second echo 2 s later. Calculate i) The speed of sound in air. ii) The distance between the cliffs. [4] ii) iii) Question 9 a) Calculate the mass of water at 80 0C needed to just melt 200g of ice at 00C. [ Sp. Latent heat of ice = 336000 jkg-1 Sp. Heat cap. of water = 4200 jkg-1 0C-1] [3] b) The diagram given below is the simple diagram of a motor. Observe it and answer the questions that follow i) ii) iii) c) i) ii) In which position A or B the couple acting on the coil is maximum? Identify the polarities of the battery at the ends P and Q. State one way to increase the speed of rotation of the coil. [3] Calculate the maximum current drawn by a hair dryer rated 550W, ]220V. The diagram below shows an electromagnet. 1. State the polarities at the ends A and B. 2. State one way to intensify the magnetic field of the electromagnet shown. [4] 5 Question 10 a) The diagram below shows a ring system of wiring. Observe the diagram and answer the questions that follow. i) Identify the terminals P,Q and R for live, neutral and earth wires. ii) Name and state the function of the part shown as A. iii) Name and state the function of part shown as B. b) Observe the circuit diagram and calculate i) c) i) ii) iii) The resistance of the circuit ii) The current in 4 [3] resistor. [3] From the equation given below identify the nuclear reaction. State the reaction by which stars generate their energy. Rewrite and complete the nuclear reaction. 1. 2. [4] 6
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