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PEARL DROP SCHOOL ICSE Ist Preliminary Examination 2024 SUBJECT: PHYSICS CLASS-X Total Marks: 80 Date: 2nd December 2024 Time: Two hours Maximum Marks: 80 Time allowed: Two hours Answers to this Paper must be written on the paper provided separately. You will not be allowed to write during 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 A is compulsory. Attempt any four questions from Section B. The intended marks for questions or parts of questions are given in brackets [ ] SECTION A (40 Marks) (Attempt all questions from this Section.) Question 1 Choose the correct answers to the questions from the given options [15] (Do not copy the question, write the correct answers only) (i) (ii) A body of mass 2 kg falls from a height of 25m. The energy it possesses at any instant is (Take g = 9.8m/s-2): a) 49.0 J b) 490 Wh c) 245 J d) 490 J A total reflecting right angled isosceles prism can be used to deviate a ray of light through a) 30 b) 60 c) 75 d) 90 (iii) For a machine used as a force multiplier a) Effort E < Load L b) Effort E >Load L c) Effort E = Load L d) Cannot be determined (iv) A body is released from a height. During its motion in striking the ground, the quantity that does not change is: a) Momentum b) Kinetic Energy c) Mechanical Energy d) Potential Energy (v) During his experiments with a single movable pulley, Jas determined the effort, mechanical advantage and efficiency as X, Y & Z, respectively. Subsequently, after lubricating the pulley thoroughly, he recalculated the effort, MA and efficiency as X', Y' & Z' respectively. Which of the following relationships accurately represents the scenario? a) X > X b) Y < Y c) Z > Z d) Z = Z (vi) Assertion: A switch will serve the purpose of making and breaking a circuit when it is connected to the neutral wire. Reason: Neutral wire is at zero potential. a) Both Assertion and Reason are true, and the Reason is the correct explanation of the Assertion b) Both Assertion and Reason are true, but Reason is not the correct explanation of the Assertion c) Assertion is true, but the Reason is false. d) Both Assertion & Reason are false. (vii) The maximum magnifying power of a convex lens of focal length 5 cm can be a) 25 b) 6 c) 8 d) 10 (viii) Assertion: Magnification of a real image is always positive. Reason: Real images are always formed inverted and below the principal axis. a) A and R both are right b) A is right R is wrong c) A and R both wrong d) A is wrong and R is right. (ix) 150 g of ice at 00C needs _________ heat to melt. [Specific latent heat of ice = 336000 J kg-1] a) 5050 J b) 50400 J c) 50.40 J d) 540 J (x) The wavelength of violet rays is 4000 nm, then its frequency is: a) 7.5x1014 b) 4 x1014 c) 7.5x1012 d) 4 x1014 (xi) In an atom, when an electron moves around the nucleus in a circular path, the centripetal force is a) Electrostatic force of attraction by the electron on the nucleus b) Electrostatic force of attraction by the nucleus on the electron c) Electrostatic force of attraction by the electron on the proton d) Electrostatic force of attraction by the nucleus on the proton (xii) The nuclear radiation which gets deflected towards negatively charged plate in an electric field is: a) Gamma b) Ultraviolet c) Beta d) Alpha (xiii) An electric appliance has a rating of 100 W and 120 V. Then the resistance of element of appliance when in use is: a) 1.2 b) 144 c) 0.83 d) 100 (xiv) Which of the following combinations have the same equivalent resistance between X and Y? (xv) The daughter element formed after beta emission is an a) Isotope b) Isobar c) Isotones d) Isomer Question 2 (i) (ii) (iii) Complete the following by choosing the correct answer from the backet [6] a) The moon revolving around the earth is in ____________ equilibrium. [static/dynamic/linear] b) The angle of deviation for red colour R is _______ than angle of deviation of violet colour V. [more /same /less] c) The conversion of part of energy into undesirable form is _______. [kinetic energy/ degradation/ potential energy] d) With increase in temperature of a gas, the speed of sound _____. [increases/decreases/remains same] e) Ultraviolet radiations have wave length from ______ to ____. [1000 / 100 / 4000 ] 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. [2] Name a material which is used for making the standard resistors or resistance wires. Give a reason. [2] Question 3 (i) (ii) (iii) (iv) (v) (vi) (vii) A steering wheel of diameter 0.4m is rotated anti-clockwise by applying two forces each of magnitude 5N. Draw a diagram to show the application of forces and calculate the moment of forces applied. [2] (a) Compare the speeds of light of wavelength 4000 (i.e. violet light) and 8000 (i.e. red light) in vacuum. (b) How is the refractive index of a medium related to the speed of light in it and in vacuum or air? [2] Differentiate between nuclear fusion and nuclear fission. [2] The clouds are seen white. Explain. [2] It is observed that the house circuits are arranged in a parallel combination. Give two advantages of this arrangement. [2] An electric heater of power 600 W raises the temperature of 4.0 kg of a liquid from 10.0 C to 15.0 C in 100 s. Calculate (a) the heat capacity of 4.0 kg of liquid, and (b) the specific heat capacity of liquid. [2] (a) What is meant by Resonance? (b) State two ways in which Resonance differs from Forced vibrations. [3] SECTION B (40 Marks) (Attempt any four questions) Question 4 (i) The given figure shows a point source P inside a water container. Three rays A, B and C starting from the source P are shown up to the water surface. (a) Show in the diagram, the path of these rays after striking the water surface. The critical angle for water-air surface is 48 . (b) Name the phenomenon which the rays A, B and C exhibit. [3] (ii) (iii) What device other than a plane mirror, can be used to turn a ray of light through 180 ? Draw a diagram in support of your answer. Name an instrument in which this device is used. [3] What is lateral displacement? Draw a ray diagram showing the lateral displacement of a ray of light when it passes through a parallel sided glass slab. [4] Question 5 (i) (ii) (iii) The diagram given below in fig. shows the position of an object OA in relation to a converging lens L whose foci are at F1 and F2. [4] (a) Draw two rays to locate the position of the image. (b) State the position of image with reference to the lens. (c) Describe the three characteristics of the image. (d) Describe how the distance of the image from the lens and the size of the image change as the object move towards F1. Figure below shows a boy standing inside a swimming pool. His legs appear shorter when his friend observes him from the pool side. If the depth of the pool is 0.8 m, calculate the distance of the image of his feet as seen from the surface of the water. (Refractive index of water = 4/3] [3] A concave lens is a focal length 30 cm. Find the position and magnification (m) of image for an object placed in front of it at distance 30 cm. State whether the image is real on virtual? [3] Question 6 (i) (ii) (iii) (iv) Explain why scissors for cutting cloth, may have blades longer than the handles, but shears for cutting metals have short blades and long handles.[2] A boy weighing 40kgf climbs up a stair of 30 steps each 20cm high in 4 minute and a girl weighing 30kgf does the same in 3 minutes. [3] Compare: (a) The work done by them. (b) The power developed by them. The diagram shows a uniform bar supported at the middle point O. A weight of 40 gf is placed at a distance 40cm to the left of the point O. How can you balance the bar with a weight of 80 gf? [3] State two differences between the centripetal and centrifugal force. [2] Question 7 (i) (ii) A longitudinal wave of wavelength 1cm travels in air with a speed of 330m/s. Calculate the frequency of the wave. Can this wave be heard by a normal human being? [3] The diagram below shows three different modes of vibration P, Q and R of the same string of a givens length. (a) Which vibration will produce a louder sound and why (b) Which vibration will produce sound of maximum shrillness (of pitch) and why? And (c) What is the ratio of wavelength of vibrations P and R? [3] (iii) When a tuning fork [vibrating] is held close to ear, one hears a faint hum. The same [vibrating tuning fork] is held such that its stem is in contact with the table surface, then one hears a loud sound. Explain. [4] Question 8 (i) (ii) Give two differences between ohmic and non-ohmic resistors. The diagram in figure shows a three-pin plug. Label the three pins. (a) Why is top pin thicker and longer than the other two? (b) Why are the pins splitted at the ends? [2] [2] (iii) (i) The music system draws a current of 400mA when connected to a 12V battery. [3] (a) What is the resistance of the music system? (b) The music system is left playing for several hours and finally the battery voltage drops and the music system stops playing when the current drops to 320mA. At what battery voltage does the music system stop playing? (a)What are radio isotopes, give an example? [3] (b) State two uses of radio isotopes. Question 9 (i) (ii) (iii) The diagram below shows a cooling curve for a substance: (a) State the temperatures at which the substance condenses. (b) The temperature range in which the substance is in liquid state. [4] (c) Why do we prefer ice to ice-cold water for cooling a drink? Explain. State the effect of presence of impurity on the melting point of ice. Give one use of it. [3] A block and tackle system has 5 pulleys. If an effort of 1000 N is needed in the downward direction to raise a load of 4500 N, calculate: (a) The mechanical advantage, (b) The velocity ratio, and (c) The efficiency of the system. [3]
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