Formatting page ...
Bunts Sangha R.N.S Vidyaniketan Vijayanagar, Bengaluru-40 III Preparatory Examination 2020-21 Sub: PHYSICS CLASS 10[ICSE] M ax M arks : 80 Date: 0 .0 .2021 Time: 2 hour ______________________________________________________________________________________ Answers to this paper must be written on the paper 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 section A and section B. The intended marks for questions or parts of questions are given. ______________________________________________________________________________________ SECTION A ATTEM PT ALL THE QUESTIONS QUESTION 1 (5 = ) 1. a) What happens to the power of an object when the object moves in a circular motion b) What happens to the power if the time for doing a work is reduced from t second to second? 10 2. Define the following (a) Becquerel rays (b) background radiations 3. Write two difference between natural and forced vibrations 4. Where does the position of centre of gravity lies for a) Uniform hexagonal lamina b) Boomerang 5. A scooter mechanic can open a nut by applying 120N force while using a lever of 50cm in length. How long handle is required if he wishes to open it by applying a force of only 40N QUESTION 2 (5 = ) 1. Draw a ray diagram for the following cases a) To show the first focus position of convex lens b) To show the second focus position of concave lens 2. What change, if any, would you expect in the characteristics of a musical sound when we increase : (a) its frequency (b) its amplitude 3. 2kg of water is contained in 1250W kettle. Calculate the time taken for the temperature of water to rise from 250C to 1000C 4. An object 6cm tall is placed on the principal axis of a convex lens. Its 3cm tall image is formed on the screen placed at a distance of 30cm from the lens. Calculate the focal length of the lens. 5. a) Write the mathematical form of Joules law of heating b) How should the electric lamps in a building be connected? QUESTION 3 (5 = ) 1. A child hears an echo from a cliff 4 second after the sound from a powerful cracker is produced. How far away is the child from the cliff? Given speed of sound in air is 340ms-1 2. a) What do you mean by the statement efficiency of a machine is 60% b) Why is a machine not 100% efficient? 3. Mirage is an optical illusion which occurs during hot summer a) Name the optical phenomenon responsible for mirage b) State any one condition for the above phenomenon 4. Complete the ray diagram having critical angle is 42 0 with making necessary angles 5. Draw a circuit diagram using dual switches to light staircases electric light QUESTION 4 1. Do all the radiations emitted in a single radioactive decay? Why? 2. Find the equivalent resistance between a and b (5 = ) 3. State two conditions of echo heard by the observer. 4. The ratio of the amplitudes of two waves is 4:9. What is the ratio of their intensities 5. The heating element of storage water heater is of 3kW power. How much energy is consumed if the heater is operated for 15 minutes? SECTION B ATTEM PT ANY FOUR QUESTIONS QUESTION 5 (3+3+4) 1. A uniform meter scale of weight 50gf is balanced at the 40cm, when a weight of 100gf is suspended at the 5cm mark. a) Draw the diagram for the above arrangement b) Where must a weight of 80gf be suspended to balance the meter scale 2. In a hydropower plant, stored water of mass 3000kg falls from a height of 100m Per second. Calculate the following (take g = 10ms-2) a) Initial potential energy of water b) The kinetic energy of water that rotates the turbine of power station c) If only 50% of the kinetic energy of water is utilised to produce electrical energy, find electrical power generated. 3. Draw a labelled diagram of a block & tackle of 5 pulleys marking the directions of load, effort and tension forces in each string a) How is load and tension forces related to each other? b) If distance moved by load is 4m, then by how is the distance moved by effort? c) Find the mechanical advantage, if efficiency decreases to 60% QUESTION 6 (3+3+4) 1. An erect, diminished and virtual image is formed. When an object is placed between the optical centre and principal focus of a lens a) Name the type of lens which forms the above lens b) Draw a ray diagram to show the formation of image with the above characteristic 2. When the object is placed in water and is viewed from air a) Is refractive index greater or lesser than one b) Which property of light is responsible for this observation c) Draw a ray diagram to show the formation of image with the above characteristic. 3. An object of height 3cm is placed at a distance of 24cm from a convex lens of focal length 10cm, when the image is formed on the screen on the other side of the lens. Calculate the following a) Power of lens b) The distance of the screen from the lens c) The size of an image d) Write the characteristics of an image QUESTION 7 (3+3+4) 1. The diagram shows the displacement time graph for a vibrating body a) Name the type of vibration produced by the vibrating body b) Name the forces responsible for such vibrations? c) Give an example of a body producing such vibrations 2. An observer situated between two parallel cliffs emits an intense sound. Two successive echoes, then heard after 5s and 7s. Calculate the distances between the cliffs. Take velocity of sound 340ms-1 3. a) Write the relationship between loudness and intensity of a sound wave b)What is the audibility range of safe limit of sound level in dB for? c) Dropping a pin has minimumsound level, what is the value of intensity and frequency of such wave? QUESTION 8 (3+3+4) 1. a) State the principle of calorimeter b) Write the relationship between heat capacity and specific heat capacity of a substance. c) Why water is used in fomentation and also as a universal coolant? 2. A piece of ice is heated at constant rate. The variation of temperature-time graph is as shown. a) What does the part ABand BC represents. b) Why DE is longer than BC in the graph? 3. An edible oil of mass 50g is heated to 120 0C and then dropped into the calorimeter vessel of mass 45g. When some pieces of silver of mass 70g at 250C is added to vessel. Calculate the final temperature. Given SHC of oil, vessel and silveris 0.5Jg -1K -1, 0.4Jg-1K-1 and 0.2Jg-1K-1. QUESTION 9 (3+3+4) 1. a) Write the mathematical form of Joules law of heating. b) What is the voltage of the electricity that is generally supplied to a house? c) What is consumed while using different electrical appliances, for which electricity bills are paid? 2. An electrical appliance is rated 1500W, 250V. This appliance is connected to mains of voltage 250V. Calculate the following a) The current drawn in the circuit b) The electrical energy consumed in 80 hours c) The cost of electrical energy consumed at a rate of `4.50 per commercial unit. 3. In given circuit diagram there are two switches S1 and S2 are used. Calculate a) The resistance if S1 switch is closed b) The current drawn from circuit when both S1 & S2 is closed c) Potential difference across 8 resistor. QUESTION 10 (3+3+4) 1. a) State one advantage of connecting the appliances in parallel b)How are the following factors depend on rise in temperature of fuse wire (i) Current rating (ii) Radius of wire 2. a) Why is fuse wire fitted in a porcelain casing? b)To which wire should the metallic case of the geyser be connected? c)Write two characteristics of a high tension wire 3. An imaginary radioactive element 92X 235decays to form X 1, X 2, X 3, X 4, X 5 and X 6 nuclides by ejecting two -particle, followed by -particle and again two -particle, followed by -particle. Represent the various nuclear changes in the form of an equation. State the mass number and atomic number of X 6. List the isotopes and isobars in the above equation. ***************************
|
