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GOKULDHAM HIGH SCHOOL &JUNIOR COLLEGE SECONDARYSECTION (2023-2024) PRELIMINARY EXAMINATION SUBJECT:PHYSICS(SCIENCE PAPER ) coHAA ALLOCuIE MARKS: 80 GRADE: 10 DATE: 16.01.2024 TIME: 2hours Answers to this Paper must be written on the paper provided separately. Youwill 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 iscompulsory. Attempt any four questions from Section B. The intended marks for questions or parts of questions are given in brackets [| This paper consists of 11 pages SECTION A (Attempt all questions from this section) Question 1 Choose and write the correct answers to the questions from the given options: [15) (Do not copy the question, write the correct answers only) (i) What provides the necessary centripetal force when an electron moves around the nucleus? a) Gravitational force b) Electrostatic force c) Magnetic force d) Nuclear force (ii) Work done is negative when a) force causes displacement in its own direction b) force causes displacement at an acute angle c) force causes displacement in opposite direction d) force causes displacement in perpendicular direction (ii) The algebraic sum of moments of weight of all the particles constituting the body about its centre of gravity is a) zero b) positive c) negative d) greater than equal to zero 1 PHYSICS (SCIENCE P GRADE 10 (iv) In a musical concert sitarist adjusts the tension and plucks the In this manner he is adjusting: a) Amplitude of sound stringPAPERI suitably. b) Loudness of sound c) Frequency of sound d) Intensity of sound (v) The symbols for 5 different nuclides are given below: 3 X Nuclidel Nuclide 2 Nuclide3 X Nuclide 4 374 Nuclide5 Which twO nuclides are isotopes of the same element? a) b) c) d) (vi) Nuclide l and Nuclide 2 Nuclide 4 and Nuclide 5 Nuclide 2 and Nuclide 3 Nuclide 2 and Nuclide 5 Assertion (A): In the visible spectrum of light, red light is more energetic than green light. Reason (R): The wavelength of red light is more than that of green light. a) Both assertion and reason is correct. Reason is the correct explanation of the assertion. b) Both assertion and reason is correct.Reason is not the correct explanation of the assertion. c) Assertion is correct but reason is not correct. d) Assertion is not correct but reason is correct. (vii) The length of a given cylindrical wire increases by 100%. Due to consequent decrease in diameter, the change in the resistance of the wire will be: a) b) c) d) 50% 100% 200% 300% 2 GRADE 10 (viii) PHYSICS(SCIENCE PAPER ) According to New International Convention, colours for live, wire (respectively) is a) Brown, light blue, green neutral and earth b) Light blue, green, brown c) Green, brown, light blue d) Red, black, green (ix) Same tune is being played on both drums A and B. Which of the following graphs represent their loudness: a) AAA Drum A Drum B Drum A Drum B b) c) AA Both Drum A and DrumB d) AAA Both Drum A and Drum B (x) Twinkling of star can be explained by the phenomenon of a) atmospheric reflection b) atmospheric dispersion c) total internal reflection d) atmospheric refraction 3 PHYSICS(SCIENCE PAPER I) at a steady rate as shown in the graph A liquid loses heat to the surroundings represents solid cooling down? given below. Which part of the graph GRADE 10 (xi) a) PQ b) QR P Temperature( C) c) RS d) QS R S Time(s) (xii) A transformer cannot raise or lower a D.C. supply voltage because a) there is no need to change the D.C. voltage b) D.C. circuit has more power losses c) Rate of change of magnetic flux due to direct current is zero d) input d.c. voltage is not sufficient for a transformer to function (xii) Amonochromatic ray refracts such that its angle of refraction is 90 as ittravels from a) water to air b) air to water c) air to glass d) water to glass (xiv) The angle of incidence for a ray of light which suffers minimum deviation of 38 through an equilateral prism is a) 45 b) 48 (xv) c) 490 d) 50 The focal length of a convex lens increases when it is immersed in water. [alg refractive index of glass with respect to air, ay = refractive index of water with respect to air , wg refractive index of glass with respect to water, gla = refractive index of air with respect to glass) Which of the following is the correct reason for it? a) whg <alg b) whg alg c) alwalg d) alg= gla 4 GRADE 10 PHYSICS (SCIENCE PAPER D Question 2 () (a) Which class of lever has advantage always greater than . Draw a labelled line diagram mechanical for such a lever. (b) State the main energy change taking place in a running d.c. motor. (ii) Draw a ray diagram to illustrate how a convex lens can be used to obtain an image of unit magnification. (iii) |21 A beam pivoted at one end has a force of0.75 kgf acting vertically upwards on it as shown in the figure given below. The beam is in equilibrium. Calculate the weight of the beam in SI unit showing all working. 0.75 kgf 2.0 cm 3.0 cm Pivot |21 Weight of the beam (W) (iv) (a) Why is it generally colder after a hailstorm than during or before the hailstorm? [21 (b)Name one source of external backgroundradiation. (v) The graph given below represents energy change of a body falling down from height h. State which line ( AB or AD or CD )shows changes in the kinetic energy of this body? (J) Energy Give reason for your answer. Co (vi) Height (m) B h (2] Rohan is designing a cell. He experiments by I) Increasing the distance between the electrodes II) Changing the electrolyte used Which of the above change/s cause change in the (a) Electro motive force (E.M.F.) (b) Internal resistance 12] 5 GRADE 10 PHYSICS(SCIENCE PAPERI) (vi) (a) Give one reason: Ultrasonic wave is used for sound rang1ng. (b) How does the speed of ultrasonic in a medium compare(less than, equal to, more than)with speed of audible sound (human range) in the same medium? Question 3 () The diagram shows a point source of light B,a convex lens L and a plane mirror M, perpendicular to the principal axis. Light rays from B, after passing through the lens become parallel to the principalaxis. M (1) (a) To which position on the principal axis will the rays return : to O , to B, to right of B? (b) What is the distance OB known as? |2| In a power circuit, which wire is connected to the (a) switch? (b) metallic body of an appliance? (ii) A machine lifted a load of 373 kgf to a height of 8 m in 20 seconds |21 .Calculate: (a) work done (b) power developed ( in HP) by it. (Take g 10 Nkg) (iv) Compare the heat capacities of the following ,giving reason for your answver: |21 Asolid iron ball of radius 1.5 inch weighing 2kg. (a) (b) (v) A hollow iron ball of radius 6 cm weighing 2kg. State two ways to safely handle radioactive material. 6 GRADE 10 PHYSICS(SCIENCE PAPER I) SECTION B (Attempt any four questions) Question 4 (i) (a) Which of the following monochromatic rays travel faster in water: Indigo or orange? (b) For any two optical media l and 2., writethe relation between 12 and 2l1. (ii) (c) Name the principle on which the above relation in (b) is based. (a) A coin kept in abeaker is not visible when seen from point P on one |3) side. But, when water is poured in the beaker, the coin becomes visible from point P. P A (a) (b) (c) (ii) (a) Which is the physical quantity represented by the ratio AC:AB ? What difference will be observed in height AB if water is replaced by a liquid having higher refractive index than water ? [3] Write your observation when the coin is viewed from point Q. Copy and complete the path of the monochromatic ray AB through the glass prism of critical angle 42 till it emerges out of the prism when it is incident as given in the diagram: 45 P B R A (b) Which face/s of the prism will appear shiny like a mirror in the above |4| Case ? 7 PHYSICS (SCIENCE PAPERI) GRADE 10 Question5 Concave Lens () Image Objecl Principal focal polnt the box. (a) Identify the spherical lens inside in the figure above and shown as lens from 4cm at |3| (b) If the image forms distance. object the find focal length is 6cm, is a suitable material for making copper whether reason, giving (1) State (a) Fuse wire? (b) Calorimeter? (c) Standard resistors? (ii) (a) (3| dark in outer space. Give reason: Sky appears blue from earth but is studied using a rock salt (b) Name the electromagnetic radiation which prism. having the longest (c) Name the electromagnetic radiation which is wavelength Question 6 (i) |4] upwards and downwards Two forces each ofmagnitude 4N act vertically length 5.5 m respectively at the two ends A and B of a uniform rod of undergoes clockwise which is pivoted at its mid-point O. The rod rotation due to these forces. (a) Draw a diagram of the arrangement. (b) pivot O. Find the resultant moment of forces about the (iii) (a) (3| 3 Draw a well-labelled diagram of a pulley system with Velocity Ratio and Mechanical Advantage 2.4. answer. (b) Is this system of pulley ideal? Give reason for your 8 (3| GRADE 10 (ii) PHYSICS (SCIENCE PAPER I) A body of mass 'm' is initially at rest, at point A. Then it is allowed to fall down and reaches point B after falling by 'x' distance. Height of point Ais 'h'. (a) Calculate kinetic energy and potential energy (b) (c) m at point B. What is the total mechanical energy at any time during the fall? At which point are the kinetic energy and Potential energy equal?( B or Cor D) B h C h/2 (4] Question7 (1) A man stands in front of a tall vertical cliff and fires a gun. He hears an echo after 5 seconds. On moving 160 m closer to the cliff, he again fires a shot,this time he hears the echo after 4 seconds. Calculate (a) initial distance of man fromn the cliff. (b) speed of sound in air. (ii) (3] Which of the radioactive radiation (a) can cause severe genetic disorders? (b) can cause maximum ionization? (c) is attracted towards the positive plate when subjected to an electric field? (ii) (a) [3] State the type of vibrations in the examples below: (I) When the handle of a vibrating tuning fork is pressed on a table , we feel a slight vibration in the tabletop too. (I)A wine glass starts vibrating when a note of a particular frequency is struck and breaks finally. (b) Distinguish between the vibrations identified in (I) and (II) by giving 2 points of difference. [4) Question 8 (i) (a) Atwhat voltage is the alternating current supplied to our houses? 9 GRADE 10 PHYSICS (SCIENCE PAPER ) (b) Two fuse wires of same length are rated 5A and 20 A. Which of the fuse wires is thicker and why? (ii) |3| The following circuit diagram shows three resistances 22,42 and R2 connected to a cell of e.m.f. 2V and internal resistance 32. Main current of 0.25A flows through the circuit. R2=R2 R=4 Q Ry=2 Q 0.25A E=2Vr=32 (a) The heat energy dissipated in 42 resistor in l minute. (b) Total resistance of the circuit. (c) The value of R. (ii) (a) The isotope ofUdecays by alpha emission to an isotope of thorium (Th).This thorium isotope further decays by beta emission to an isotope of protactinium (Pa). Write down the equations to represent these two nuclear changes, clearly showing changes in atomic number and mass number, if any. (b) The given diagram shows a shaded area where the direction of a magnetic field is into the page. A beam of beta particles enters the magnetic field as shown in the diagram, below : |3| A Beam of Beta particles X X X X X X Y I) II) X X Magnetlc Field Directed into B X the Pago Y Will the magnetic field affect the beam of beta particles? In which direction (towards A or B or C) willthe beam of beta particles move as they enter the magnetic field? 10 [4] GRADE 10 PHYSICS(SCIENCE PAPER I) Question 9 40 gm of ice at 0 C is used to bring down the temperature of a mass of water at 60 C to 10 C.Find the mass of the water used. () certain [specific heat capacity of water =4200 Jkg c Specific latent heat of fusion of ice = 336 x10 Jkg] [3| (1) (a) Two materials Aand Bhave specific heat capacities in the ratio 2:3. 1f they are supplied with same amount of heat then which material will show greater rise in temperature given their masses are the same? Give reason for your answer. (b) What energy change would you expect to take place in molecules of a substance when it changes its state from liquid to solid without change in its temperature? [3] In the following diagam, an arrow shows the motion of the coil (ii) towards a bar magnet. A Bar magnet Coil (a) If the induced current is flowing from A to B, state the polarity of the X end of the bar magnet. (b) Name the law used to come to the conclusion in (a). (c) What is the reason for this induced current? (d) State one way to increase the magnitude of the induced current using the same apparatus? ***** 11 [4|
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