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PHYSICs-STD X Maximum Marks: 80 Time allowed- Two hours must be written on the paper proviaded separately. Answer.s to this Paper You will not be allowedIto write during the first 15 minutes. This time is to be The time given at the head of thisspent in reading the Question Paper. paper is the time allowedfor writing the answers. This Paper is divided into two Sections. Section Ais compulsory. Attempt any four from Section B The intended marks for questions or parts of questions are given in brackets [J. SECTION A(40 Marks) (All questions are compulsory) Question 1 Choose the correct answers to the questions from the given options. (i) (i) (Do not copy the question, write the correct answers only.) Aconverging lens has a focal length 40cm. Calculate its power. (a) -1.5 D (b) -2.5 D (c) +2.5 D (d) +1.5D During B-emission (a) the mass number and atomic number decrease by lamu. (b) the mass number remains unchanged, but the atomic number decreases by 1amu. (c) the mass number increases by Tamu, but the atomic number remains the same. number remains increases by I amu. (d) the mass (ii) unchanged, but the atomic number If two convex lenses are in contact with each other. power decreases (a) the diverging converging power decreases the (b) power increases converging (c) the power increases diverging (d) the [15] (iv) Assertion (A): The moment of force depends upon the magnitude of the force applied and the perpendicular distance of the line of action of force from the axis of rotation. Reason (R): The opening and shutting of the door is possible due to the moment of force. (a) Both Aand Rare true and Ris the(YYCt ex pltinelioY ol (b) Both Aand R are true but R is not the correct explanation of A. correct explanation of A: (c) A is true but R is false. (d) Both A andR are true. (v) Whichof the following does not produce a sound wave? (a) Anexplosion in outer space (b) A bell ringing underwater (c) A hammer hitting a block of rubber (d) A gun fired in a room with no echoes (vi) Aray of red light enters a semi-circular glass block normal to the curved surface.Which diagram shows the partial reflection and refraction of the ray? b d) c) (vi) Observe the circuit diagram given alongside. read the statements givel below and find out the statement that correctly explains the fault in the circuit. L The resistors R and R2 have not been correctly connected inparallel. R |I, The voltmeter has not bcen correctly connected in the circuit. IL The ammeter and the key have not been correctly connected in the circuit. K (a) Only I (b) Only| (c) Both I and || (d) Both Il and II| "ThisExamination- 2024-25 - Phystcs Std X- Prelimimary ghJanuary2025 pages paper consists of 10 printed Page 2 (vii) ohishuNan Current is Ilowing through ncoil as shown in the figure, Which one ofthe given figures will depict the magnetic polarity and the direction of the alongthe axis of correct ly lines of force the coil? (a) (ix) (c) (d) Thenuclcus of an atom consists of )46 ncutrons and 95 protons. Itdecays after emitting an alpha particle. How many protons and neutrons are left in the nucleus after an alpha cmission? (a) (b) (c) (d) (x) (b) Protons 93, neutrons =142 Protons 95, neutrons 144 Protons 93, neutrons -144 Protons 95, neutrons =142 The amount of hcat energy required to melt a given mass of substance at as the: its melting point without point any rise in its temperature is called (a) Specific heat capacity (b) Specific latent heat of fusion (c) Latent heat of fusion (d) Specific latent heat of freezing (xi) Radio 107.8. Madhav wants to tune into Asanjo and after tuning, he he notices some interruptionsstation. Which radio is able to tune into the Madhav? phenomena is used by (a) Electrical tuning (b) Resonance (c) Radar (d) Sonar (xii) (xii) the darkness the owl or the bat emits: in prey To locate its (a) infrasonic waves (b) sonic waves (c) infrared waves (d) ultrasonic waves switchedon the electric is energy flashlight energy When a and light then to heat energy changes to (a) first changes to heatenergy (b) directly changesto light energy energy and (c) directly to heat then to light energy changes first (d) shisnu\an During the Sunset, the colour whichscatters closest tothe eye of the (xiv) observer is: (a) red (b) yellow (c) violet (d) blue (xv) Two notes are produced from a flute and plano, such that they have the same loudness and same pitch. The notes so produced differ in their (a) Speed (b) Waveform (c) frequency (d) wavelength Question 2 (i) Complete the following by chosing the correct answer from the bracket: (a) Lenz'slaw is based on [6] electromagnetism/ Lorentz force/ Conservation of energy. (b) The atoms having different numbers of protons but the same number of neutrons are called as isotones/isobars/isotopes. (c) A switch is an on-off device for voltage/resistancelcurrent in a circuit. (d) The presence of resonant bodies near the vibrating body increases/decreases/remains same the loudness of sound. (e) The centre of gravity of a uniform ball is its bottom/at its topmost point/at its geometric centre. at Ameter scale is balanced in the horizontal nosition as shown in the figure (ii) [2] given below. Find the value of w. 60 cm 4Ocm w (ii) [2] Compare the following: (a) the ionising powers and (b) penetrating powers of a, and y radiations. Question3 () Sumit observes that there is an air bubble in the water. Doesthis air (2] bubble behave like alens? If yes, what type oflens doesit actlike? Std X - This paper of nrinted r1ges 2025 Page + shishuNvan If live wire makes accidental contact with the metal case, which circuit (A or B) in the diagram, illustrating an electric iron, is considered safe for the (i) (2] user? Atuse is present in the live wire ofhoth circuits. Justify your answer. A B Metal Case 220 V Metal case Coil 220 V Electric Electric iron Iron (a) What should be the angle between the direction of force and the direction of displacement, for work to be negative? (b) Name the physical quantity obtained using the formula Uh where isthe potential energy and h is the height. U (iii) (iv) pressed at its free end A metal foot ruler is held at the edge of a table. It is [2] [2] and then released. It vibrates. (a) Name the vibrations produced. vibrations. (b) State one way to increase the frequency of these thermonuclear reaction? (a) Why is a nuclear fusion reaction called a (b) Complete the reaction: + Energy 4He2 t Hez +2H, (v) (vi) A magnet kept at the centre of two Coils A shown in and B is moved to and fro as (2] (2] deflection. the diagram. The two galvanometers show 4 Soft iron Coil B Coil A State with a reason whether: x>y or x<y. [x and y are (vii) magnitudes of substances Thermal capacities of then: Aand R are the same. If the mass of A the mass ofB IS more (a) than Which substance will| have more specific heat capacity? substance will show a greater rise in if the Which (b) ofheat is supplied to Sameamount (viii) deflection.) both? temperature Name a single pulleyin which displacement of load and effort is not the Same. [2] shishu\an SECTION B (Atempt any four questions fromn this section) Question 4 () The image of a candle flame placed at adistance of 36 cm from aspherical [3] lens, is formed on a screen placed at a distance of 72 cm from the lens. Calculate the focal length of the lens and its power (ii) The diagram (not drawn to the scale) [3] angle of alongside shows the graphical relation deviation () between angle of deviation and angle of incidence when light passes through a triangular prism of angle 620 of a certain glass material. a)ind niinmum deicho(0.0) b) inc (a) A mixture of red + blue + green is passed through a convex lens as shown in the diagram below. State (iii) gle of X incidence () 14] lens Red + blue + green whether the ray passes through a single point or different points in the principal axis after refraction. (b) Name the invisible radiations which are studied using the quartz prism. (c) State one use of these radiations. (d) Name oneradiation having a wavelength longer than the wavelength of these radiations. Question 5 () O is a luminescent particle trapped inside a [4] glass block. A student traces the path of rays coming out of it and reflecting over a plane mirror as shown in the diagram Glass block alongside. Complete the table, using the labels from the figure. The first label is done for you. Sr. no (a) (b) (c) (d) (e) Description Anangle of reflection on the Apartially reflected ray in mirror A critical angle Arefracted ray An angle of Std X -- Label the glass slab refraction of the ray R This paper consists of 10 printedpages January 2025 Preliminary Examination- Physics 9th Page 6 shishuNran (a) A coin kept inside water Iu=4/31 when viewed from air in a vertical direction appears to be raised by 3.0 mm, Findthe depth of the coin (i) [3] in water. (b) How is the critical angle related to the refractive index of a medium? (a) Infrared radiations are used in warfare. Explain with reason, why. (b) A ray of light is incident at 450 on an equilateral prism in the diagram below. (ii) Incident light [31 60 45 Red Violet 60 I) Name the phenomenon exhibited by the ray of light when it enters and emerges out of the prism. 2) State the cause of the above phenomenon mentioned by you. Question 6 A metal rod AB of length 80 cm is balanced at 45 cm from the end A () with 100 gf weights suspended from the two ends. 40 100gf 45 Fulcrum 80 100 gf (a) If this rod is cut at the centre C, then compare the weight of AC to the weight of BC. (b) Give a reason for your answer in (a) (i) system. The diagram shows a block-and-tackle complete the labelled diagram showing the (a) Copy and correct connection ofthe tackle and the direction of the forces involved to obtain maximum V.R. with the convenient direction. (b) Calculatethe M.A. ofthis pulley system if its efficiency is 80%. (3] shishu\an (ii) The figure below shows a simple pendulum of mass 200 g. It is displaced from the mean position A to the extreme position B. The potential energy (4) at position A is zero. At position B, tne pendulumbob is raised by 5 m. B (a) What is the potential energy of the pendulum at the position B? (b) What is the total mechanical energy at point C? (c) What is the speed of the bob at position A when released from B? t (Take g 10ms and given that there is no loss of energy.) Question7 () (i) A person standing in front of a cliff fires a gun and hears its echo after 3s. [4] If the speed of sound in air is 336 ms!. (a) Calculate the distance of the person from the cliff. (b) After movinga certain distance from the cliff, he fires the gun again and this time the echo is heard 1.5 s later than the first. Calculate the distance moved by the person. (a) Which characteristic of sound is affected due to the larger [3] surface of a school bell? (b) Calculate the distance covered by the Ultrasonic wave having a velocity of 1.5 kms! in 14 s. when it is received after reflection by the receiver of the SONAR. (ii) Aradioactive nucleus Xemits an alpha particle followed by two beta particles to form nucleus Y. (a) With respect to the element X, where would you positionthe element Y in the periodic table? (b) What is the general name of the element X and Y. (c) If the atomic number of Yis 80 then what is the atomic number of X? This paper Std X - Preliminary consists of 10 prrinted pages nuary2025 Page 8 shishuvan Question 8 (i) Pooja's friend John wants to control the oven from two diagram. connecta fuce to his oven. He wants to different locations. Shown below is his circuit Fuse (3) 220VA.C ven CO (a) Which one of the two, A or B should be a live wire? (b) In the event of an overload, will the fuse serve its (c) What is the meaning of the statement that the bulbpurpose? iis rated 600 W, 220 V? (ii) (a) Copy and complete the following nuclear reaction. 232Rn [3] Po + -X (b) What will be the effect on the radiation X, emitted in the above reaction when it is allowed to pass through an electric field? (ii) A magnet is released along the axis of a copper coilas shown in the diagram. N - magnet entering OB -magnet leaving (a) State the polarity at the top end of the coil when the magnet (b) leaves the coil. The direction of the current is from Ato B when the magnet enters the coil. What will be the direction of the current when coil? magnet leaves the (C) the Name the law which can be used to determine the direction in the coil the induced current of (d) State one wayto increase the magnitude of the induced current in the coil. Consists of 10 This paper amination- 2024-25 printed pages [4] shishu\ans Question 9 cooling curve for a substance: The diagram below shows a () [3] temperaturec 150 60 10 time (0,0) the substance condenses. State the temperatures at which substance is in liqujd state. (b) The temperature range in which the (a) cooling a (c) Why do we prefer ice to ice-cold water for (ii) drink? it down from 75 C What mass of ice at 0 C added to 2.lkg water, will cool [31 oC-!,Specific to 25 C? Given: Specific heat capacity of water =4.2 Jgl latent heat of ice=336 Jg. (ii) Observe the given circuit diagram and answer the questions that follow: 22 52 32 (a) Calculate the resistance of the circuit when the key K completes (b) Calculate the current through 30 resistance when the circuit is complete. the circuit. O00000000OOAI| the bestO00999YY [4]
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