Formatting page ...
The Assembly of God Church School 125/1 Park Street, Kolkata-700017 Pre - Board Examination-2017-2018 _____________________________________________________________________________ PHYSICS SCIENCE Paper 1 (Two hours) Answers to this Paper must be written on the 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 given at the head of this Paper is the time allowed for writing the answers. _____________________________________________________________________________ _ Section I is compulsory. Attempt any four questions from Section II. The intended marks for questions or parts of questions are given in brackets [ ]. _____________________________________________________________________________ _ SECTION I (40 Marks) Attempt all questions from this Section. Question 1 a) Can the heat capacity of a substance be infinite? Justify your answer. [2] b) i) What is indicated by the ratio of change of current to change of voltage of V-I graph? ii) The slope of V-I graph of an ohmic conductor makes an angle 30 to the current axis. What is the resistance of the conductor? [2] c) i)What is measured by the unit Sievert (Sv)? ii) Give one example of internal source of background radiation. [2] d) A convex lens of focal length 15 cm is placed on a horizontal mirror. A pin is placed above the lens such that there is no parallax between the pin and its image. Draw a neat diagram to show this effect. What is indicated by the height of the pin from the lens? [2] e) When a body moves in a circular path how much work is done? Give reason. [2] Question 2 a) Momentum of a particle of mass 2 kg is 10 Ns. What is the speed and energy of the particle? [2] b) Does the boiling point of water change with altitude? If so, how? [2] c) Is it possible to burn a piece of paper using a convex lens in day-light without using matches or any direct flame? Draw a diagram to support your answer. [2] d) In case of single movable pulley show that t is gained in force is lost in speed . [2] e) A uniform metal wire has resistance of 80 . It is cut into four equal lengths. Find the equivalent resistance when three parts are connected in parallel and fourth part is in parallel with them. [2] Question 3 a) What is electron volt? Find out the ratio of kW and MeV? [2] b) Some portion of a filament of a room heater is removed and re-joined. It is connected to same power supply. Whether the bulb will glow brighter or dimmer? Explain [2] c) State the energy changes which take place the following: i) Photosynthesis in green leaves. ii) charging a battery. [2] d) A circular coil carries current in clockwise direction. What magnetic pole induces at its centre? Show two magnetic lines of force around the coil. [2] e) State any two difference between musical sound and noise. [2] 1|Page This paper consists of 4 printed pages. Question 4 a) Which of the two, 1g ice at 0 C or 1g water contains more heat? Give reason to your answer. [2] b) State any two properties of gamma radiation. [2] c) To use a machine as a force multiplier what class of lever should be preferred? Draw a sketch of such a lever. [2] d) The figure shows three resistors each of resistance 4 forming the three sides of a an equilateral triangle ABC. What is the equivalent resistance between the points A and B of this circuit? If these points are connected to a 1.5 V cell, what is the current drawn from the cell? [2] e) A mass of lead is embedded in a block of aluminium. Radiation from a radioactive source incident on one side of the block produce a shadow on a fluorescent screen placed beyond block. The shadow of aluminium is faint but the shadow of the lead is dark. Give reason for this difference. [2] SECTION II (40 Marks) Attempt any four questions from this Section Question 5 a) Obtain the expression for the kinetic energy of a body. How is it related with the momentum of a body? [3] b)A block and tackle has two pulleys in each block, with a tackle tied to the hook of the lower block and the effort being applied upwards. Draw a neat diagram to show this arrangement and calculate its mechanical advantage. [3] c) A uniform seesaw, 5m long, is supported at its centre. A boy weighing 40 kgf sits at a distance of 1m from the centre of the seesaw. i) To which class of lever does it belong? ii) Draw a diagram of the arrangement showing the fulcrum (F), load (L) and effort (E) with their directions. ii) Find where a girl of weight 20 kgf must sit on a seesaw so as to balance the weight of the boy. [4] Question 6 a) A ray of light enters a glass slab PQRS, as shown in in the diagram. The critical angle of the glass is 42 . Copy this diagram and complete the path of the ray till it emerges out from the glass slab. Mark the angles in the diagram wherever necessary. [3] b) A lens forms the image of an object placed at a distance 15 cm from it, at a distance 60cm in front of it. Find the i) the focal length, ii) the magnification, and iii) the nature of image. [3] c) i) Explain why radium paint, consisting of zinc sulphide and a trace of radium salt, glows in the dark. 2|Page ii) What type of prism is used to study ultraviolet radiation and infrared radiation and why? [4] Question 7 a) The stem of a vibrating fork is pressed against a table top. Answer the following questions: i) Will the above action cause any special type of vibration? If yes name it. ii) Under what condition does the above action lead to resonance? [3] b) i) A thin watch glasses is partially filled with glycerine. What type of lens is this liquid forms? ii) Power of a lens is +2D. What is the focal length of the lens? Weather it is a convex or a concave lens? c) i) A sound made on the surface of a lake takes 3 s to reach a boatman. How much time it will take to reach a diver inside the water at the same depth? ( velocity of sound in air = 330 ms -1; velocity of sound in water= 1450 ms-1 ) ii) An observer sitting in between two vertical walls claps 10 times per second. He adjust his distance 17 m from one wall in such a way that the sound of his clapping coinciding with the echo. Calculate the velocity of the sound. Question 8 a) i) Explain why a bunch of thin and twisted wires is used in a high tension cable? ii) A bulb is marked 100 W, 220 V and an electric heater is marked 2000 W, 220 V. What is the ratio of their resistances? In which of the above a thicker connecting wire or lead is required? b) A cell of e.m.f and internal resistance r is used to send current to an external resistance R. Write expression for i) the current drawn from the cell, ii) the p.d across the cell, and iii) the voltage drop inside the cell. c) The circuit diagram along side shows three resistances 2 4 and R connected to a battery of e.m.f 2 V and internal resistance 3 .A main current of 0.25 A flows through the circuit. i) What is the potential difference across the 4 resistor? ii) Calculate the potential difference across the internal resistance of the cell. iii) Calculate the value of R. Question 9 a) State in brief, the meaning of each of the following: 1) The heat capacity of a body a body is 50 J -1 2) The specific latent heat of fusion of ice is 336000 J Kg -1 3) The specific heat capacity of copper is 0.4 J. g. -1. b) The graph represents a cooling curve for a substance being cooled from higher temperature to a lower temperature. i) What is the boiling point of the substance? ii) What happens in the region DE? iii) Why is the region DE shorter than the region BC? [3] [4] [3] [3] [4] [3] [3] 3|Page c) Find the result of mixing 10g of ice at -10 with 10g of water at 10 . Specific heat capacity of ice = 2.1 J g -1 K-1, specific latent heat of ice = 336 J g -1 and specific heat capacity of water = 4.2 J g -1 K-1 [4] Question 10 a) i) Define radioactivity. ii) What happens inside the nucleus that causes the emission of beta particle? iii) Express the above change in the form of an equation. b) i) What is nuclear fission? Name the particle used for it. ii) State one difference between the radioactive decay and nuclear fission. c) i) State the energy change which takes place when a magnet is moved inside a coil having a galvanometer at its ends. Name this phenomenon. ii) Draw a labelled diagram of an A.C. generator. [3] [3] [4] _______________________________ 4|Page
|
