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ST. HELENA'S SCHOOL- PUNE-1 (2024-25) EXAMINATION SECOND PRELIMINARY PHYSICS Time: 2 hrs. Date: 21-01-25 Marks: HO Class: 10 Instructions: Section Ais compusory. Atlempt any four questions from section B. answer. en the same sheet as the rest of the be done must work, rough including All working, parts of questions Are given in brackets, The intended marks for questions or Section A (40 Marks) (15 x 1=15) questions from the given options. QL. Seleet the correct answeIs to the correct answer only.) (Do not copy the questions. Write the clockwise direction Then the moment of couple i)A momcnt of couple rotates a body in Is taken as c) negative d) minimum b) maximum 'h', the decrease in gravitational potential distance ii). If a stone of mass m falls a vertical cnergy is ) positive c) mgh d) mg ngh b) mh7 2 a) m) sulphide. rays produce fluorescence in zinc c) Infrared d) Ultraviolet a) Red b) Violet iv). The diagram shows 3pulley systems. Which ofthe following staicmgyts is gorrct? 32N EaSN HoN a) All pulley systems are ideal b) Two pulley systems are ideal and one is practical c) One pullcy system is idcal and two are practical d) none of the statements are corrcct. v). Assertion :A curent carrying solenoid when suspended freely sets itself in the north south direction like a bar magnet. vise Reason: The end of the solenoid where the dircction of current is anti-clock behaves asa south pol. c)A is truc and R is false a) Both A and Rare true 5) Both Aand Rare false vi), With the help of the graph the power of the lamp is d) A is false R is truc a) 20 W c) 60 W b) 40 W d) 80 W vi), in refaction of light through a prism, the light ray: a) suffers refraction only at one face of the prism b) emerges parallel to incident ray ) bends at both surlases oforis sowards its hasc prian towards apct wavelengths hctwccn P. Q and K d) bends at both sfaces of Vii). What is the ratio of a) 3:2:1 b) 1:2.3 c) 6.32 d) 34:6 p i) Ifapart of the lens is covered, its focal Jength a) tncreases b) docreases ) remains unchanged d) none of the above ) There arc two copper wires of length ratio 13hat have teir ratio 1:4 What wil be the ratio of their resistances cross-sectional arcas in tie a) 1:1 c) 3,4 b) 4:3 d) 3.2 I). Two substances P and O have the sane mass SubstancePhas higher heat Capacity than Q. What consequcnce would you obscrve whctn Pand Qspccific are leated with same amount of heat energy Pwill experience smaller tenperature change than Q b) Pwill experience larger temperature change than Q c) Both will expericnce same xii) temperature change J)PorQ depending on other factors. The radiation with maximum penetrating powcr is a) c)y b) d) X raiation xi). During melting of ice at 0 C the a) energy is releascd and temperature renains constatnt b) energy is absorbed and temperature renains constant, c) energy is releascd and temperature dcereases d) energy is absorbed and temperature increases KiV). Which one of following statements is correct? a) Live wire has zcro potential b) Fuse is connected in neutral wire c) Potential of live and carth wire is same d) Earnh wire is used to prevent shock XV). A constant curent lows in a horizontal wite in tbe plane of the paper from east to west as shown n the figure. The directian of magnetic feld al a point will be North lo South. a) directly above the wire E c)at apoimt in the plane of peper on narth of wire b) directly below the wie d) at apoint in the plane of paper on south of wire I) Complete the following by choosing the correct ansmers from the bracket. a -is an cxanple of class 3 lever ( broomstapler/'wire cutter ) b) Lenz's luw is based on law of couservstion of (forceicharge/'energy) c) Whena ray of lieht enters from denser to rarer medium( decreases /<i less than <r spoed decreases). (ultraviolet/visible/Infared) radiation bas lowest energy. (6) c) Tums ratio of step down transformer is ( cqual to 1/ less than one / more than one ) The requirca nheat energy to raise the temperaturce of lg of water through 1 C is Goule! calorickclvin) ) In the following atoms which one is a radioisotopc? Give one use of this isotope? o", c, N", He m) A non uniform tmetre scale of weight 1 N is balanced at 30 cm. Calculate the minimum force required to keep the scale in cquilibrium if it is pivoted at 0 end. (2) (2) i)a) Astone is ticd to a string and rotated in a horizontal plane. Which force nccessary for circular motion is provided by the tension in the string? What is the work done by this force at any instant ? b)What is the cnergy transformation in the exposure of photographic film in sunlight? )"he refroctive index of water is 4/3".Explain the meaning of this stateuneut. (3) (2 side of i) The graph shows Joud against effort for a lever with load and effort on same fulerum. ->E(Kgf) a) Which feature of the load- ctfort graph must be caleulitedto determine mechanical advantage ? (2) b) Which class does this lever belong to? iV) (a) Give one precaution while using a switch. (2) (b) Give one disadvantage of ring system of house wiring. the v)A boat which is stationary at a distance off 1500 m from the shore, sends a signal to coast. Ii's echo is heard in 10s. Find the velocity of sound. (2) (2) vi) Calculate the effective resistance across Aand B 2 vii) A mixture of rudioactive clements give off 3 types of adiations. n) Name the radiation which travels with the speed of light. b) Name the radintion which has the highest ionising power. SECTIONB (40 marks) Attempt any 4 qestions. QIV 0) a)A roller with a diameter of 20 cm is aised over BpavetAD by pplying forces Fl and PZ, as shown in diagram: Lfnagnitude of botuh forces i l0 N, then conpare the magnitudes of their torques FRZ 21 the force of gravity. Is the work bJA COolie raises a load upwards against done by load positive negative or zero? Why onstant specd by appiying Ablock of mass 30 Kg is pulled up a slope with a a force of 200 Nparalel to the slope (3) Pand Qare the initial and final positions of the block. Calculate the force etion of (3) offered by the surface AP9 Draw a diagram of a pulley systc1n of velocity ratio advantage if its efficicncy is 90%. 4. Calculate its mechanical (4) OV i) The diagram (not drawn to scale) below shows the graplhical relation betwecn angle of deviation and angle of incidence, when light passes trough a triangular prism of a certain glass material.. ) state the t angle of minimum deviation s of this prism and the corresponding angle of incidence. 2) Calculate the value of x. 3) Find the angle of the pris1m. (3) a) Adouble convex lens with refractive index H inside two liquids of refractive indices W2 and are shown in the diagrams bclow. The refractive indices are such that #:> and How would a parallel incidenttbeam of light refract when it comes out out of tbe lens in cach case shown above.1) in fig a 2) fig b. b)Can the refractive index of a medium be less than 1 ? a)Name the lens which gives us amagnification of -I. (3) B b)The diagram showsa lens as a combination of glass prisns of sumeT refractive index. 1)Nane the lens formed by the combination. 2)Conplete the ray diagram when AB is Between optical centre and F1. (4 QVI a)Calculate the wavelength of an clectromagnetic wave of frequency lS Mhz. b)Give one dependant factor of lateral displacement and how does it depend on it? i) (3) Theccritical cri angle for material of which the equiangular prism ABC shown in fig is made is 60 .A rny of light incident on the side AB of the prism is refracted along DE such that the angle it makes with side ACis 150 <EDB -90 .Draw the path of the incident ray on side AB (which travels along DE)and ulso the path along which ray DE travels from point Eonwards. C (3) a) Aconvex lens of power +4 D hus un objcct placcd at a distunce of 50 cm in front of the lens, 5 |) State the nature of the image formed 2) What is the definite distance, towards or away from the lens, the object should move so that the image is not seen. b)An objcct placed 50 cm from a lens produces a virtual image at a distance of 10 cm in front of the lens, Calculate the focal length of the lens. (4) QVII i) the ship which is anchored in a) A person is standing at the sea shore. An observer on The person on the shore betweena vertical clit and the person on the shore, firesthea gun of the fired gun. If the smoke hcars two sounds, 2 seconds and 3 seconds after seeing speed of sound in air is 320ms', calculate: 1) distance between observer on ship and the person on shore. 2) Distance between cliff and observer on ship his b)Which characteristic of sound, makes it possible to recognise a person by voice without seeing him? (3) from iila) It is observed that during march-past we hcar a base drum distinctly distance compared to the side drums. 1) Name the characteristic of sound associated with the above observation. 2) Give a rcason for the above observation b)A man playing a clarinet is able to produce notes of different frequencies. If he closes the holes far from his mouth, will the pitch increase or decrcase ?Give reason. iim) (3) a) Arrange the pendulums in the increasing order of their frequencies. (he lle) Walii )ifpendulum Xis initiated into oscillation, which other pendulum will oscillate with highest anplitude. 2)Give reason for your answer. b) Define echo. What is the only requirement for the reftection of a sound wave ? Q VIII In the circuit diagram below, calculate (4) I 24 a)the external resistance of the circuit b)the current I, cthe curent I (3) ii) a) In the fig the arrow represents the beam of clectrons moving in the plane of the paper from left to right. How would the beam be defiected, relative to the paper, if ()A is north pole and B is south pole? (2) A is positively charged and Bncgatively charged ? Bean b) Define specific resistance. i) a) For a scienceeerexhibition, two students A and B brought two similar exhibits. Both the exhibits consists of a coil placed in the magnetic field. StudenL A rotates the coil (2) (1) and a bulb connected to it glows. Student B passes current through the coil and the coil rotates. Name the phenomenon involved with the exhibit of student A? State the principle based on which the exhibit of student B works. 2) c) An appliance rated 440 W, 220 V is connected across 220V supply. 1) Calculate the maximun curent that the appliance can draw. (4) 2) Calculate the resistance of the appliance. Q IX i) a) Purva wants to connect a fuse to her oven which is controlled using a dual control switch. Shown alongside is the diagram. 1) Which one Aor Bis the live wire ? 2) In the event of an overload will the fuse 220 Serve it's purpose?Why? b)Why is power generated at 11 KV and not at a voltage higher than that? (3) Thenumber graph ofshows the correlation between the number of electrons (x-axis) and neutrons (y-axis) for element A in the periodic table. The element is denoted by letters rather than conventional symbols. When element A.in the graph undergoes radioactive decay, it releases radioactive decays. a3,148) 4S a) Write the chemical symbol along with mass number and atomie number for the clement denoted as A' b) Plot on the graph, I) The daughter element after emission of alpha radiation by element A. 2) The daughter clement ,as indicated in previous answer, if it undergoes beta decay. 3 a) The diagrum below shows a cooling curve for 200 g of water. The heat is extracted at the rate of 100 Js. Answer the qyestions gA 1) Calculate specific capacity of water. that follow: 2) Calculate specific latent heat of freczing of water. (0,0 storing fruits and vegttubles in a m e warchouses in c) Water tubs are kept Countries in winter. Why? d) Drinks get coolcd more quickly by adding picces of ice than ice cold water at 0 C.Wh? (4)
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