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- I V I B GYOR HIGH VIBGYOR HIGH First Prellmlnary Examination 2023-2024 PHYSICS Grade: X Max. Marks Date : 07/12/2023 Time Allowed: 2 hours : 80 INSTRUCTIONS: Answers to this paper must be written on the paper provided separately. You will not be allowed to write during the 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. The intended marks for questions or parts of questions are given alongside the questions. Section I is compulsory. Attempt any four questions from Section II. This question paper consists of 13 printed pages. SECTION I (40 Marks) Attempt all questions from this Section. Question 1 [15) Choose the correct answers to the questions from the given options. (Do not copy the question, write the correct answers only.) (i) A bar AB pivoted at point O is acted upon by two equal forces as shown in the figure. -----d . ---~ r :I O a What will be the effect on AB? only rotational motion (b) rotational motion with translational motion (c) neither rotational motion nor translational motion (d) only translational motion 1 I . lilGfi (ii) (iii) (iv) (v) (vi) The kind of energy possessed by a falling raindrop: (a) only kinetic energy (b) only potential energy (c) both kinetic and potential energy (d) none of these In a block and tackle system, the efficiency can be increased by: (a) reducing the weight of pulleys in the lower block (b) reducing the friction in the bearings of the pulleys (c) (d) increasing the number of pulleys in the lower block both (a) and (b) - Which statement about a-particles anq f3-particles is correct? (a) a-particles are less ionising than f3-particles.)\ (b) a-particles are more penetrating than f3-particles~ (c) a-particles have greater mass than f3-particles. (d) a.aparticles have the same charge as f3-particles. The diagram below shows the phenomena of a mirage in the dessert. This is an example of: (a) (b) Refraction and total internal reflection of light Reflection of light (c) Dispersion of light (d) Scattering of light Which diagram shows the correct path of a light ray through a glass block kept in air? 2 Vi I IB G! YO R HIGH (a) (b) glass glass (d) (c) glass glass (vii) The diagram given below represents a sound wave. The sound wave changes from X to Y. _y X Which statement about the sound wave is correct? (a) The amplitude of the wave is increasing. (b) The frequency of the wave is decreasing. (c) The pitch of the sound is increasing. (d) The loudness of the sound is decreasing. (viii) A student attaches a thin strip of metal to a table such that one end of a metal strip is fixed, while the other end is free. The strip begins to vibrate when he presses the strip's free end and releases it. How can he reduce the frequency of that vibration? 3 i 4 V 1 tB G V OR HIGH (ix) (a} By increasing the length of the strip (b) By putting a small mass at the free end of the strip (c) By decreasing the length of the strip (d) Both (a) and (b) are correct Assertion (A): Tungsten metal is used for making the filament of incandescent lamps. Reason (R): The melting point of tungsten is very low. (x) (a) Both A and Rare true and R is the correct explanation of A. (b) Both A and R are true but R is not the correct explanation of A. (c) A is true but R is false . (d) A is false but R is true. A class is designing a d.c. motor. To achieve a greater turning effect, three suggestions are made. 1) Have a larger current in the coil of the motor. 2) Have a stronger magnet in the motor. 3) Increase the number of turns in the coil. Which suggestions will help to increase the turning effect? (a) 1,2and3 (b) 1 and 2 only (c) 1 and 3 only. (d) 2 and 3 only 4 V I ;B G: VO R HIGH (xi) The diagram shows an electric generator with the coil in a vertical position . magnetic poles coil 0 to oscll16Scop8 . slip rings ___ r. ---,,..,...f-\---c brushes Which row describes the generator? The generator produces The induced e.m.f. becomes zero when the coil is horizontal (a) a.c. (b} a.c. the coil is vertical (c) d.c. the coil is horizontal (d) d.c. the coil is vertical ? (xii) The thermal capacity of object Y is greater than that of object Z. . What is the consequence of this? (a) Object Y needs less thermal energy to melt it than object Z. (b) Object Y needs less thermal energy to raise its temperature by 1 c than object Z. (c) Object Y needs more thermal energy to melt it than object Z. (d) Object Y needs more thermal energy to raise its temperature by 1 c than object Z. (xiii) Two different metal bodies A and B of equal,mass are heated at a uniform rate under similar conditions. The variation of temperature of the bodies, with time, is graphically represented as shown in the figure. The ratio of their specific heat capacities is: 5 V 118 G Y O R HIGH gts ' 0 D. 12 0 90 A / - 60 ,/ 3 o !L: 1 (a) 8:3 (b) 3:4 (c) 3:8 4:3 (d) 2 B _, .- I-'" 3 4 s 6 llmc (t tnin.) 7 8 \,\~~ ?I (xiv) The rays used in night-vision devices to observe animals or people, without the observer being detected, are: (a) Ultraviolet rays (b) Infrared rays (c) Visible light (d) Gamma rays (xv) The diagram shows a light ray entering a glass block and travelling towards point 0. Angle i=25 , the critical angle of the glass is 42 . Which path does the ray take after reaching O? A D light ray (a) OA (b) OB (c) OC (d) OD 6 V I ,s GYOR HIGH Question 2 (i) (a) State the law of conservation of energy. (b) State the energy changes taking place in the following cases: [3] 1. An air gun is loaded and fired. 2. Glowing of a torch bulb. (ii) A wheel of diameter 2 m is shown in the figure below with axle at 0. A [21 force F= 2N is applied at B in the direction shown in the figure. Calculate the moment of force about: (a) tl=le centre 0. (b) the point A. '1/ I F=2N1---.-,,,,.,lli+--- A (iii) (a) Rishi went to a palmist -to show his palm. The palmist used a [2] special lens for this purpose. State the type of the lens'. (b) (iv) Give reason: There are more than one image formed in a thick glass mirror. The following figure shows a mixed source R of alpha and beta particles in a thick lead walled container. The particles pass through a magnetic field in a direction perpendicular to the plane of paper inwards as shown by x. X X X X X X X X X X X X X X X X X X X X X X X X (a) Show in the diagram how the particles get affected. (b) Name the law used in part (a). 7 [2] HIGH (v) (a) State whether the specific heat capacity of a substance remains the same when its state changes from solid to liquid. (b) Give an example to support your answer. Draw a displacement-time graph for a body executing free vibrations in vacuum. [2] (vii) A divergent lens has a focal length of 20 cm . At what distance should an [2] (vi) object be placed in front of the lens, so that its image is formed 10 cm away from the lens. "" \ - (i) (ii) (iii) (v) ,o \ -:.\ .,.o State two points of difference between nuclear fusion and nuclear fission. [2] Name the following radiations: (a) that has the highest penetrating power. (b) that are used to sterilize surgical equipments. State the conditi?_~ wh~n .on applying a force, a body produces: (a) translational motion (b) (iv) B."'I io to - , ""J - ~-tit, Question 3 I (a} Identify the type of transformer used for the above purpose. (b) State the turns ratio of the above transformer. A crowbar of length 120 cm has its fulcrum situated at a distance of 20 cm from the load. (b) [2) rotational motion A transformer is used to change a high alternating e.m.f. to a low alternating e.m.f. of the same frequency. (a) [2) [2) [2] Which class of lever is this? Calculate the mechanical advantage of the crowbar. SECTION II (40 Marks) Attempt any four questions from this Section Question 4 (i) A uniform metre scale balances horizontally on a kn.ife edge placed at 55 cm mark, when a mass of 25 g is supported from one end. (a) Draw the diagram of the arrangement. (b) Calculate mass of the scale. 8 [3] V I 18:G: Y'O R HIGH (ii) (a) The diagram shows a satellite revolving around the earth. What is [3] the work done by the satellite? ~,.. . .-- Satcllltir ti (b) A boy weighing 350 N runs up a flight of 30 steps, each 20 cm high in 1 minute. Calculate the work done. (iii) (a) [4] Identify the class of lever used in a human body when: 1. the head is raised off the chest 2. when we hold a book on the palm of the hand. (b) A block and tackle system of pulley has a velocity ratio 4. Draw a labelled diagram of the system indicating clearly the points of application and directions of load and effort. Question 5 (i) [3] (a) (b) What is a total reflecting prism? Draw a neat diagram to show how a total reflecting prism is used to turn a ray of light through 180 . (ii) (a) (b) Give reason: The sky at noon appears white. Figure 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 = ~] 3 [3] f iJ:jifil iJ HIGH (iii) (a) One half of a convex lens of focal length 10 cm is covered with a black paper as shown in the diagram. A 2Fl 30cm Can such a lens produce a complete image of an object placed at a distance of 30 cm from the lens? (b) Draw a ray diagram to show the formation of the image in the above case, if the lens is not covered with black paper. Question 6 (i) An electric bulb rated 220 V, 60 Wis working at full efficiency. Another identical bulb is connected in series with the first one and the [3] system is connected across the mains as shown in the diagram below: 220V Mains (a) (b) (ii) (a) (b) Calculate the total power. What will be the power, if the bulbs are connected in parallel? Explain the meaning of the statement 'current rating of a fuse is 5A'. In the transmission of power, the voltage of power generated at the 9enerating stations is stepped up from 11 kV to 132 kV before it is transmitted. Why? (c) State one characteristic property of a copper wire which makes it unsuitable for use as a fuse wire. 10 [3] V I fB G' Y O R N (iii) (a) HIGH ame two factors on which the magnitude of an induced e.m.f. [4] in the secondary coil of a transformer depends. (b) In th e following diagram an arrow shows the motion of the coil towards the bar magnet. B (1) State in which direction the current flows, A to B or B to A? (2) Name the law used to come to the conclusion. Question 7 (i) (a) A man stands at a distance of 68 m from a cliff and fires a gun. [3] Calculate the time interval after which an echo will be hear.d, if 1 (b) the speed of sound in air is 340 ms ? If the man had been standing at a distance of 12 m from the cliff would he have heard a clear echo? (ii) The ore of Uranium found in nature contains 2 2 i~u and i~u . Although [3] both the isotopes are fissionable, it is found out experimentally that one of the two isotopes is more easily fissionable. (a) Name the isotope of Uranium which is easily fissionable. (b) (c) Give a reason for your answer. Write a nuclear reaction when Uranium 238 emits an alpha particle to form a Thorium (Th) nucleus. (iii) (a) Name the phenomenon involved in tuning a radio set to a (b) particular station. Define the phenomenon named by you in part (a) above. (c) What do you understand by loudness of sound? (d) In which units is the loudness of sound measured? Question 8 (i) A radioactive nucleus X emits an alpha particle followed by two beta particles to form nucleus Y. 11 [4] (3] V I 1B-t G,i Y4 0 R HIGH (a) With respect to the element X, where would you position the element Y in the periodic table? (ii) (b) What is the general name of the element X and Y? (c) If the atomic number of Y is 80 then what is the atomic number of X? The diagram below shows a dual control switch circuit connected to a bulb. 3 A (iii) supply (a) Copy the diagram and complete it so that bulb is switched on . (b) Out of A & B which one is the live wire and which one is the neutral wire? The diagram below shows a circuit with the key k open. Calculate: 2Q k 3Q 5Q ,____ ~.__ __ _____, 3.3 V. 0.5 .Q (a) the resistance of the circuit when the key k is open. (b) the current drawn from the cell when the key k is open. (c) the resistance of the circuit when the key k is closed. (d) the current drawn from the cell when the key k is closed , 12 [3] (4] I V I 18 G V O R HIGH Question g (i} A large lump of ice was heated and it changed state. The following [3] figure shows how th e temperature varied with time. 150 D 100 C Temperature 50 in c B 0 -50 (ii) I I I I A 0 I I I I I I I I I 100 50 150 200 250 Time in seconds (a) Which part of the figure shows the process of melting? (b) Which part of the figure shows the process of water boiling? (c) State the change in energy of water molecules when there is a rise in temperature. 1 1 A calorimeter of mass 50 g and specific heat capacity 0.42 J g- "C- [3] contains some mass of water at 20 C. A metal piece of mass 20 g at 100 C is dropped into the calorimeter. After stirring, the final temperature of the mixture is found to be 22 C. Find the mass of water used in the calorimeter. 1 1 [specific heat. capacity of the metal piece= 0.3 J g- C- ; specific heat 0 10 (iii) 1 capacity of water= 4.2 J g- C- ] Is it possible that a glass lens placed in a transparent liquid (a) becomes invisible? Justify your answer. (b) [4] Two parallel rays of red and violet travelling through air is incident on the air-glass boundary as shown in the figure. Will their paths inside the glass be parallel? Give reason for your answer. air glass ***** I ,' ;' 13 .J
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