Formatting page ...
PRATIMA PALANDE SCHOOL (ICSE Board) st 1 Preliminary Examination Physics SCIENCE Paper 1 STD:X MAX. MARKS: 80 WRITING TIME: 2 hour READING TIME: 15 MINS INSTRUCTIONS: 1. Answers to this paper must be written on the paper provided by the School. 2. You will not be allowed to write during the first 15 minutes. This time is to be spent in reading the Question paper. 3. The time allotted for writing and uploading the answer scripts is mentioned on the top of the paper. 4. Please note that the time limit shown by the software is the time allotted for writing. 5. At the end of writing time, you will be provided an additional 20 minutes. This additional time is given for you to scan your answer sheets and upload them as a single PDF file. Please ensure that you utilise this time exclusively for the purpose mentioned. 6. The system will not allow you to upload your answer sheets beyond the allocated time. Attempt all questions from Section I and any four questions from Section II The intended marks for question or parts of the questions are given in the brackets [ ]. SECTION I Attempt all questions from this section Question 1 (a) (i) Does the position of centre of gravity of a body change when the body is deformed. Justify your answer. (ii) State a factor on which the position of center of gravity of a body depends. [2] (b) A satellite revolves around the earth in a circular path. What is the work done by the satellite? Justify your answer. [2] (c) Why is magnification positive for a concave lens, while it can be positive as well as negative for a convex lens? [2] (d) Light of a single colour is passed through a liquid having a piece of glass suspended in it. On changing the temperature of liquid, at a particular temperature the glass piece is not seen. When is the glass piece not seen and Why? (e) Name the pulley which has no gain in mechanical advantage. State the purpose of such a pulley. Question 2 (a) (i) A beam of monochromatic light undergoes minimum deviation in an equiangular prism, how does the beam pass through the prism, with respect to its base. (ii) If white light is used in the same way as in part (i) above, what change do you expect in the emergent beam. (b) State two factors which affect the loudness of a sound heard by a listener. [2] [2] (c) A metal wire of resistance 6 is stretched to twice its original length. Calculate the new resistance. [2] Page 1 of 5 (d) A current of 2 A is passed through a coil of resistance 75 for 2 minutes. (i) How much heat energy is produced? (ii) How much charge is passed through the resistance? [2] (e) Is it possible to deflect radiations in a way similar to and particles, using the electric or magnetic field? Give reasons. [2] Question 3 (a) Complete the following sentences: (i) Water can be made to boil at 115 C by _____________ pressure over its surface. (ii) The melting point of a substance ____________ by addition of impurities in it. [2] (b) (i) With reference to the direction of action, how does the centripetal force differ from a centrifugal force? (ii) Compare the magnitudes of centripetal and centrifugal force. [2] (c) State the factors on which resistivity depends. [2] (d) Can a concave lens form an image of size two times that of an object ? Justify. [2] (e) A ray of light incident at an angle of incidence i1 passes through an equilateral glass prism such that the refracted ray inside the prism is parallel to its base and emerges at an angle of emergence i2 . (i) State the relation between i1 and i2. (ii) State the value of angle of deviation in such a situation. [2] Question 4 (a) A bulb of power 40 W is used for 12.5 h each day for 30 days. Calculate the electrical energy consumed. [2] (b) (i) A spanner has a long handle. Why? (ii) A uniform metre rule is pivoted at its mid-point. A weight of 50 gf is suspended at one end of it. Where a weight of 100gf should be suspended to keep the rule horizontal [2] (c) When a troop crosses a suspension bridge, the soldiers are asked to break their steps. Why? [2] (d) Derive a relationship between efficiency, M.A. and V.R. for a machine. [2] (e) In a central heating system, steam enters the radiator pipe at 100 C and water leaves the radiator pipe at 100 C, can this radiator pipe be used to heat up the room? Justify. [2] SECTION II Attempt any four questions from this section Question 5 (a) (i) State the SI unit of specific resistance. (ii) Two wires A and B are made of copper. The wire A is long and thin while the wire B is short and thick. Which will have more specific resistance? Justify your answer. (iii) Is current a scalar or a vector quantity, Justify. [3] (b) A uniform metre rule balances horizontally on a knife edge placed at the 58 cm mark when Page 2 of 5 a weight of 20gf is suspended from one end. (i)Draw a diagram of the arrangement. (ii)What is the weight of the rule? [3] (c) The diagram in figure shows the displacement-time graph of a vibrating body. (i) Name the kind of vibrations. (ii) Give one example of such vibration. (iii) Why is the amplitude of vibrations gradually decreasing? (iv) What happens to the vibrations of the body after some time? [4] Question 6 (a) (i) Which material is used for making a calorimeter? Give two reasons. (ii) How is the loss of heat due to radiation minimised in a calorimeter? [3] (b) Show the non-occurrence of total internal reflection through a 30 , 90 , 60 prism with the help of necessary diagrams (mark all the angles). [3] (c) A pulley system with a velocity ratio 4 is used to lift a load of 300 kgf to a vertical height of 10 m by applying an effort of 100 kgf in the downward direction. (i) Draw the arrangement of pulleys showing the Load, Effort and Tension in each strand. (ii) Calculate the efficiency and work done by the effort. [4] Question 7 (a) (i) State the principle of moments. (ii) State two conditions for a body, acted upon by several forces to be in equilibrium. (iii) Is it possible to have an accelerated motion with a constant speed? Name such type of motion. [3] (b) In figure A, B, C and D are the four pendulums suspended from the same elastic string XY. The lengths of pendulum A and D are equal, while the length of pendulum B is shorter and of the pendulum C is longer. The pendulum A is set into vibrations. (i) What is your observation about the vibrations of pendulum D? (ii) Give reason for your observation in part (a). (iii) What type of vibrations take place in pendulums B and C? [3] Page 3 of 5 (c) Two resistors of 4 and 6 are connected in parallel. The combination is connected across a 6 V battery of negligible internal resistance. (i) Draw a circuit diagram, (ii) Find the current through the battery and the current through each resistor. [4] Question 8 (a) An object of height 4 cm is placed at a distance 24 cm in front of a convex lens of focal length 8 cm. (i) Find the position and size of the image (ii) State the characteristics of the image. [3] (b) An engine can pump 30,000 litres of water to a vertical height of 45 m in 10 min. Calculate the work done by the machine and its power. (density of water = 103 kg/m3). [3] (c) (i) State two difference between heat capacity and specific heat capacity. (ii) Why the base of a cooking pan made thick and heavy? [4] Question 9 (a) (i) A uniform half-metre rule can be balanced at the 29.0 cm mark when a mass 20g is hung from its one end. Draw a diagram of the arrangement and find the mass of the half-metre rule. (ii) State the SI unit of moment of force. [3] (b) (i) An electric kettle is rated 3 kW, 250 V. Can this kettle be used in a circuit which contains a fuse of current rating 13 A. Explain. (ii) The V-I graph for a series combination and for a parallel combination is as shown in the figure Which of the two lines (A or B) represents the parallel combination? Give a reason for your answer. [3] (c) (i) A man standing in front of a vertical cliff fires a gun. He hears the echo after 3 s. On moving closer to the cliff by 82.5 m, he fires again and hears the echo after 2.5 s. Find the distance of the cliff from the initial position of the man and the speed of sound. (ii) A man is standing at a distance of 12m from a cliff. Will he be able to hear a clear echo of his sound? Give a reason for your answer. [4] Page 4 of 5 Question 10 (a) A power circuit uses a cable having three different wires. (i) Name the three wires and state between which of the two wires should the heating element of an electric geyser be connected? (ii)To which wire should the metal case of the geyser be connected? Justify your answer. [3] (b) (i) A radioactive substance is oxidized. What changes would you expect to take place in the nature of radioactivity? Explain your answer. (ii) How many alpha and beta particles are emitted when Uranium nucleus to lead nucleus . Justify your answer. decays [3] (c) The circuit diagram in figure shows three resistors 2 , 4 and R connected to a battery of e.m.f. of 2 V and internal resistance 3 ohm. If current of 0.25 A flows through the circuit, find: (i) the potential difference across the 4 ohm resistor (ii) the potential difference across the internal resistance of the cell, (iii) the potential difference across the R ohm or 2 ohm resistor, and (iv) the value of R. [4] ----------------------------------------------------END------------------------------------------------------------------------- Page 5 of 5
|
