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KAPOL VIDYANIDHI INTERNATIONAL SCHOOL(ICSE) TEMPLE OF KNOWLEDGE Date:05/12/22 STD X MARKS:80 PRELIM 1 EXAMINATION PHYSICS DUR: 2h 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. Attempt all questions from each section A. Any 4 questions from section B. SECTION A (All questions are compulsory) Q.1 (a) (b) (c) (15) The frequency of a sound produced from a source in the air is 20Hz. If the sound is produced when the source is in water, the frequency ______________. a. Decreases b. Increases c. Remains the same d. Cannot predict The unit of electric current is __________. a. ampere b. coulomb/second c. volt/ohm d. all the above A conducting wire carries current in the downward direction. Then the direction of the magnetic field created around is _________. a. clockwise b. parallel to the conductor c. anticlockwise d. along the direction of current flowing in the conductor (d) When a radioactive substance is heated, its radioactivity _______________. a. increases b. decreases c. increases and then decreases d. remains the same (e) One dioptre is _____________ a. focal length of the lens in metre c. reciprocal of focal length in metre b. reciprocal of focal length d. reciprocal of focal length in cm (f) A van was moving with a velocity of 20m/s and slows down to 10m/s to take a turn. If the van has a mass of 600kg, the work done by it to take to this turn is _____________. a. 9 104 J b. 9 10-4 J c. 9 103 J d. 9 10-3 J (g) An object is Vibrating at 4000 Hz. The time period of sound produced is ______. a. 0.0025 sec b. 0.025sec c. 0.00025sec d. 0.0005 sec (h) Two identical weights are attached to opposite ends of a beam. Both are 1m from the pivot. If the weight on the right hand side is moved closer to the pivot, __________________. a. the beam rotates clockwise b. the beam will not rotate c. the beam rotates anticlockwise d. the beam will be in equilibrium (i) A ball of mass 0.20kg is thrown vertically upwards with a velocity 20m/s. The maximum potential energy attained by the ball is ____________. a. 40J b. 47J c. 49J d. 50J (j) The front face of a circular loop of a wire is North-pole, the direction of current in this face of the loop will be: a. Clockwise b. Anticlockwise c. Towards North d. Towards South (k) Which one of the following statements is correct? a. Live wire has zero potential b. Earth wire is used to prevent electric shock c. Fuse is connected to the neutral wire d. Potential of live and earth wire is always the same (l) (m) (n) (o) The radiation with maximum penetrating power is __________. a. alpha radiation b. beta radiation c. gamma radiation d. all have same penetrating power Resonance is _________________. a. A forced vibration in which amplitude remains constant b. A forced vibration in which the frequency of forced vibration is greater than the free vibrations of the body c. A forced vibration in which the frequency of forced vibration is equal to the free vibrations of the body d. A forced vibration in which the frequency of forced vibration is less than the free vibrations of the body While entering from medium A to medium B, if the light slows down then _____________. a. angle of incidence is less than the angle of refraction b. angle of incidence is equal to the angle of refraction c. angle of incidence is greater than the angle of refraction d. angle of incidence is zero Which property of water that makes it an efficient coolant? a. specific heat capacity of water being very low b. specific latent heat of water being infinitely high c. specific heat capacity of water being zero d. specific heat capacity of water being high Q.2 (a) (b) A uniform meter scale is in an equilibrium position. Calculate the mass of the ruler. (15) (2) When a ray of light passes from air to glass, the ray does not get deviated. Give reason. (2) Write two properties of ultrasonic waves used in echo depth sounding. (2) (d) Draw a ray diagram to illustrate how a ray of light incident obliquely on one face of a rectangular glass slab of uniform thickness emerges. (2) (e) What do you mean by the following statements? i. The heat capacity of a body is 50 JK-1 ? ii. The specific heat capacity of copper is 0.4 Jg-1 K-1 ? (2) (f) Joe has three wires made of copper, tungsten and nichrome with him. Which among these should he use as a conducting wires for his electrical circuit. Justify your choice. (2) (g) Name the rays: a. used to take photography at night and fog b. used in industry to check welding c. used for sterilizing surgical instruments (3) (c) Q.3 (a) The centre of gravity for a body lies outside the body. State whether the statement is true/false with a suitable example. (2) (b) The radioactive beta decay, an electron comes out of the nucleus. Explain. (2) (c) (d) (e) State two conditions for the body to be in equilibrium (2) Define the commercial unit of electricity. How is it related to joule? (2) List two factors on which lateral displacement depends. (2) SECTION B (Any 4 questions of 6) Q.4 (a) (4) i. Copy and complete the ray diagram to show the formation of the image of the object AB ii. Name the lens LL' iii. Name a device in which this principle is used. (b) Cathy fires a gun towards a hill and hears its echo after 5seconds. She then moves 320m towards the hill and fires again. This time she hears the echo after 3seconds. Calculate the velocity of sound. (c) i. Write any one essential condition for total internal reflection to take place. ii. How is the critical angle related to the refractive index of the medium? iii. Name one factor on which the critical angle depends. (3) (3) Q.5 (a) A body, when acted upon by a force of 10kgf, gets displaced by 0.5m. Calculate the work done by the force in S.I. units when the displacement is: i. In the direction of force applied ii. At 90 to the force applied iii. Opposite to the direction of force applied iv. Power gained if the time taken to displace the body by 0.5m in 5s in the direction of force applied. (b) Draw a neat diagram of a single movable pulley with a fixed pulley. Write an advantage of this combination (c) From the circuit given below, find: i. Value of R ii. Potential difference across the 4ohm resistor iii. Potential difference across the 2ohm resistor (4) (3) (3) Q.6 (a) Prove with all necessary steps and a diagram that the total mechanical energy remains constant for a freely falling body. (b) i. Which lens, a thick one or a thin one has more focal length? ii. Find the power of the lens of focal length 20cm (3) (3) (c) Two copper wires, A and B, are in the same length at 30 C, the radius of A is twice that of B. i. Which wire has a greater resistance? Justify your answer. ii. Which wire has greater resistivity? Justify your answer. (4) Q.7 (a) (b) Draw the displacement time graph for a body performing damped vibrations and free vibrations (4) Copy and complete the diagram given below and mark all relevant angles: (3) (c) Q.8 (a) A nucleus 194 82 X emits an alpha particle: i. What will be the atomic number of the daughter nucleus Y? ii. What will be the number of neutrons in the daughter nucleus Y? iii. Write a nuclear reaction showing the emission of this particle. (3) From the graph, (3) i. Identify which among A and B represent the parallel connection of resistors. Justify your answer. ii. What does the slope of the above graph provide you? (b) (c) Q.9 Define the term centre of gravity. Locate the centre of gravity of: i. Cylindrical rod ii. Triangular lamina Figure shows the variation in temperature with time when some wax cools from the liquid phase to the solid phase. i. In which part of the curve, the wax is in liquid phase? ii. What does the QS of the curve represent? iii. In which part of the curve, the wax will be in liquid as well as solid phase? iv. In which part of the curve, the wax is in the solid phase? (3) (4) (a) A pulley system has a velocity ratio of 4 and an efficiency of 90%. Draw a neat and labelled diagram and calculate: i. Mechanical Advantage ii. The effort required to raise a load of 300N by the system (4) (b) i. The power rating of a device is 60W, 240V. What is the meaning of this statement? ii. Find the value of safe current which can pass through this device. (3) (c) i. What does the symbol given below represent and briefly explain its importance in an electrical circuit? (3) ii. Name the material used for making fuse wire? Write the nature which makes it suitable for this purpose.
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