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ICSE Class X Board Exam 2021 : Physics

5 pages, 67 questions, 60 questions with responses, 60 total responses,    1    0
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FATHER LEBLOND SCHOOL HALF YEARLY EXAMINATION SESSION 2020-2021 CLASS: X F.M:80 PHYSICS (THEORY) TWO HOURS Answer 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. This time given at the head of this paper is the time allowed for writing the answers. ________________________________________________________________________________________________ This paper is divided into 2 sections. Attempt all the questions from section A and any 4 questions from section B The intended marks for questions or parts of the questions are given in brackets [ ]. _____________________________________________________________________________ SECTION A (40 Marks) Attempt all the questions Question 1: (a) Define work. State its S.I. unit. [2] (b) State two differences between centripetal and centrifugal force. [2] (c) A man exerted a force of 100 N in pulling a cart at a constant speed of 20 m/s. Calculate the power spent by the man. [2] (d) On what factor position of centre of gravity of a body depends? What is the position of centre of gravity of a rectangular lamina? [2] (e) What is the difference between uniform circular motion and uniform linear motion? [2] Question 2: (a) A light ray suffers reflection and refraction at the boundary in passing from air to water. Draw a diagram and level angle of incidence, angle of reflection and angle of refraction. [2] (b) Which colour of white light, is the refractive index of a transparent medium: (i) Least (ii) Most [2] (c) Give scientific reason: A tank appears shallow than its actual depth. [2] (d) State the essential condition for total internal refection to take place. [2] (e) A pebble kept inside water ( = 4/3) when viewed from air in vertical direction appears to be raised by 3.0 mm. Find the depth of pebble in water. [2] PKM/PHY/X THIS QUESTION PAPER CONSISTS OF 3 PRINTED PAGES TURN OVER Question 3: (a) State the condition for the following: (i) A lens has both its focal lengths equal. (ii) A ray passes un-deviated through the lens. [2] (b) (i) Define resonant vibrations. (ii) What can you say about the amplitude of a body undergoing forced vibration? [2] (c) Two wires of the same material and same length have radii 1 mm and 2 mm respectively. Compare their (i) Resistance (ii) Specific resistance [2] (d) Define internal resistance of a cell. [2] (e) What is meant by nuclear waste? State one way for the safe disposal of nuclear waste. [2] Question 4: (a) An electric bulb is rated 240 V, 100 w. What information does it convey? Calculate the current in the bulb. [2] (b) A bulb of power 50 w is used for 12 hours each day. Calculate the energy consumed in a day. [2] (c) Calculate the equivalent resistance between the points A and B. [2] 206 (d) Uranium nucleus 238 92 undergoes several disintegrations and ultimately decays to lead nucleus 82 . How many alpha and beta particles are emitted? [2] (e) How does the thickness and length of a fuse wire depend on its current rating? [2] SECTION B (40 Marks) Attempt any four the questions Question 5: (a) A boy takes 5 minutes to lift a 20 litre water buket from a 20 m deep well, while his father does it in 3 minutes. (i) Compare the work done and power developed by them. (ii) How much work is done by each of them? (Take density of water = 103 kg/m3; g = 9.8 m/s2) [3] (b) A block and tackle system has the velocity ratio 3. Draw a labeled diagram of the system indicating the points of application and the direction of load L and effort E. A man can exert a force of 200 kgf. What is the maximum load he can raise with this pulley system if its efficiency is 60%? [3] (c) A ball of mass 100 g is thrown vertically upwards with an initial velocity 20 m/s. Calculate: (i) The initial kinetic energy imparted to the ball (ii) The maximum height reached if air friction is neglected (iii) The maximum height reached if 40 % of the initial energy is lost against the air friction (iv) Name the kind of energy it will possess on reaching the maximum height. [4] PKM/PHY/X 2 TURN OVER Question 6: (a) (i) How does the angle of deviation formed by a prism change with the increase in the angle of prism? (ii) A ray of light of wavelength 6600 suffers refraction from air to glass. Taking = 3/2, find the wavelength of light in glass. [3] (b) (i) Where is the object placed in reference to the principal focus of a magnifying glass? (ii) Draw a ray diagram to show the image formation by a magnifying glass? [3] (c) A lens forms the image of an object placed at a distance of 50 cm from it on a screen placed at a distance 90 cm on the other side of it. (i) Name the kind of lens. (ii) Find the focal length of lens. (iii) Calculate the magnification of image formed. (iv) What is the nature of the image so formed? [4] Question 7: (a) In the diagram given below A, B, C, D are four pendulums suspended from the same elastic string PQ. The length of A and C are equal to each other, while the length of pendulum B is smaller than that of D. Pendulum A is set into a mode of vibrations. (i) Name the type of vibration taking place in B and D. (ii) What is the state of pendulum C? (iii) State the reason for the type of vibration in pendulum B. [3] (b) A man standing in front of a vertical cliff fires a gun. He hears the echo after 5 s. On moving closer to the cliff by 90 cm, he fires again and hears the echo after 3 s. Find: (i) the distance of cliff from initial position of man, (ii) the speed of sound. [3] (c) (i) Draw a graph of potential differences verses current for an ohmic resistor. (ii) How can you find the resistance of the resistor from this graph? (iii) What is non- ohmic conductor? (iv) State one condition for a body to execute natural vibration. [4] PKM/PHY/X 3 TURN OVER Question 8: (a) (i) In a conductor 6.25 x 1016 electron flow from its end A to B in 10 s. Find the current flowing through the conductor. (ii) What is the necessary condition for a conductor to obey Ohm s Law? [3] (b) (i) A fuse is rated 8 A. Can it be used with an electrical appliance rated 5 KW, 200 V? Give the reason. (ii) Name two safety devices which are connected to the live wire of a household electric circuit. [3] (c) The circuit diagram in fig. shows three resistor 2 , 4 , and R connected to a battery of e.m.f. 2 V and internal resistance 3 . If main current of 0.25 A flows through the circuit, find: (i) the p.d. across the 4 resistor, (ii) the p.d. across the internal resistance of the cell, (iii) the p.d. across R or 2 resistor and (iv) the value of R. [4] Question 9: (a) The diagram shows a uniform metre rule of weight 100 gf being balanced on a knife edge placed at the 40 cm mark, by suspending a weight m gf at the mark 20 cm, find: (i) the value of m. (ii) the resultant moment and its direction if the weight m is moved to the mark 30 cm. (iii) the position of another weight of 50 gf to balance the rule in part (ii). [3] PKM/PHY/X 3 TURN OVER (b) (i) State two differences between energy and power. (ii) Amit weight 60 kgf climbs up a ladder of height 10 m in 15 minutes. Calculate the increase in his potential energy and power spent by him. Take 1 kgf = 10 N. [3] (c) A pulley system with a velocity ratio 4 used to lift a load of 300 kgf to a vertical height of 10 m by applying an effort of 100 kgf of downwards. (i) Draw the arrangement of pulley showing the load (L), effort (E) and tension (T) in each strand. (ii) Find the efficiency of pulley system and the work done by the effort. [4] Question 10: (a) (i) What is a calorimeter? (ii) Name the material of which it is made of. Give two reasons for using the material stated by you. (iii) How is the loss of heat due to radiation minimized in a calorimeter? [4] (b) (i) State two differences between Heat capacity and Specific Heat capacity (ii) Give a mathematical relation between Heat capacity and specific Heat capacity. [3] 0 (c) A metal piece of mass 20 g is heated to a constant temperature of 100 C. Then it is added in a calorimeter of mass 50 g and specific heat capacity 0.42 J g-1K-1, containing 50 g of water at 200C. After stirring the water, the highest temperature recorded is 220C. Calculate the specific heat capacity of metal. Specific heat capacity of water = 4.2 J g-1K-1. [3] __________________________________________________________________________________________ PKM/PHY/X 4 END

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