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80 MT PHYSICS ICSE 2021 Syllabus Chapter 1 to 71 Time: Hundred Minutes SECTIONI [40 Marks Attempt all questions] Question 1 Two bodies A and B have masses a) in the ratio 5:1l and their kinetic 125:9. Find the ratio of their velocities. [2] ) Name the physical quantity which is measured (ii) How is calorie related to SI unit of that (c) in calories. quantity? 2 couple. () Define critical angle. (1) State one important factor which affects the critical angle of a given medium. (e) 2 (i) Define couple. (i) State the SI unit of moment of (d) energies are in the ratio (2 An electromagnetic radiation is used for photography in fog. ) Identify the radiation. i) Why is this radiation mentioned by you, ideal for this purpose? [21 Question 2 1) What is the relation between the refractive index of water with respect to air (24 ) and the (a) refractive index of air with respect to water (wa) i) If the refractive index of water with respect to air (aHw) is.Calculate the refractive index of air with A man near respect to water (wa). [2 playing a flute is able to produce notes of different frequencies. If he closes the holes mouth, will the pitch of the note produced, increase or decrease? Give a reason. [2] his diagram below shows a light source P embedded in a rectangular glass block ABCD of critical angle 42. Complete the path of the ray PQ till it emerges out of the block. [Write The necessary angles] 42 ww [2] (d) e n s is placed in water its focal instead ofair, how does length change: 121 1) Which lens, thick or thin has greater focal length? (e) Two waves of the same pitch have What will be the ratio of their () intensities and amplitudes in the ratio l. 2 (ii) frequencies? Question 3 (a) () Define resonant vibrations. (1) Which characteristic of sound, makes it possible to recognize a person by his VOICe without seeing him? b) () State and define the SI () (c) (d) [21 unit of power. How is the unit horse power related to SI unit of power? State the energy changes in the (i) An electric iron. (ii) A ceiling fan. () Why 1:1? [2] following. 2 is the ratio of the velocities of light of wavelengths 4000 and 8000 A in vacuum (i) Which of the above wavelengths has a higher frequency? (e) [21 Why is the motion of a body moving with a constant speed around a circular path said to be accelerated? ii) Name the unit of physical quantity obtained by the formula 2K/V* where K: kinetic energy, V: Linear velocity. 2 Question 4 (a) (b) The power of a lens is -5D. ) Find its focal length. (ii) Name the type of lens. 2 State the position of object in front of a converging lens if (i) lt produces real and same size image of the object. (i) It is used as a magnifying lens. (2] i) State the relation between the critical angle and the absolute refractive index of a medium. i) Which colour of light has a higher oritical angle? Red or Green light. (d) 12 () Define scattering. (i) The smoke from a fire looks white. Which of the following statements is true? 1. Molecules ofthe smoke are bigger than the wavelength of light. 2. Molecules of the smoke are smaller than the wavelength of light. 2 (2 he tollowing diagrm shows a 60, 30", 90' glass prism of critical angle 42. Copy tne diagram and complete the path of incident ray AB emerging out of the prism making tne angle of incidence on cach surface. (21 SECTIONII |40 Marks] Attempt any four questions] K e T e y t Question 5 A body of mass 10 kg is kept at a height of 5 m. It is allowed to fall and reach the ground. (1) What is the total mechanical energy processed by the body at the height is a frictionless medium? (1) What is the kinetic energy possessed by the body just before of 2 m assuming it hitting the ground? Take g= 10 ms (b) A uniform metre scale is in equilibrium as shown in the diagram. 5 cm 30 cm 100 cm Cd 40 g Caloulate the weight ofthe metre scale. (i) Which of the following options is correct to keep the ruler in equilibrium when 40 gf is shifted to 0 cm mark? Fis shifted towards 0 cm or 13 Fis shifted towards 100 cm. (c) The diagram below shows pulley arrangement. Load ) Copy the diagram and mark the direction of tension on each strand of the sting. i) What is the velocity ratio of the arrangement? 3 t n e tension acting on thie " load is raised. Cnd ot the string string is T, then wvhat is the relationship between through moves distance x, find the distance a by i and eltOTt which the 4 Question 6 How does the angle of deviation formed by a prism change with increase in the angic a graph showing the variation in the angle of with the incidence? Draw incidence b) at a prism deviation surface. aug A Virtual, diminished image is formed when an object is placed between the optical principle focus of a lens. (i) Name he type of lens which forms the above image. (1) Draw a ray diagram to show the formation of the image with the above stated and the centre characteristics. (c) (3 An object is 13 placed 24 cm in front of a convex lens of focal length 8 (i) What is the nature of the image so formed? (ii) Calculate the distance of the image from the (ii) Calculate the magnification of the image. cm. lens. 4 Question 7 (a) It is observed that during march-past we hear a base drum distinctly from a compared to the side drums. (i) Name the characteristic of sound associated with the above observation. (ii) Give a reason for the above observation. (b) A pendulum has a frequency distance of 4 vibrations per second. An observer starts the [3] pendulum and fires a gun simultaneously. He hears the echo from the cliff after 6 vibrations of the pendulum. If the velocity of sound in air is 340 ms"', find the distance between the cliff and the observer. (c) (3] Two pendulums C and D are suspended from a wire as shown in the given figure. Pendulum Cis made to oscillate by displacing it from its mean position. It is seen that D also starts oscillating. Wire O O ) Name the type of oscillation, C will execute. i) Name the type of oscillation, D will execute. 4 (11) IT the length of D is made cqual to C, then what difference will you notice in tnc oscillations of D? (iv) What is the name of the phenomenon when the length of Dis made cqa Ito C? 14 Question8 (a) () Derive a relationship between Si and CGS unit of work. () A force acts on a body and displaces it by a distance S in the direction at an angie w ith ne arection of force. What should be the value of 0 to get the maximum positive work 13 (b) metre rod is pivoted at the centre weights of 20 gf and with 12 gfsuspended at a two perpendicular distance of 6 cm and 10 cm from the pivot respectively as shown below. 50 cm 12gf 20 g 10 cm 6 cm () Which of the two forces acting on the rigid rod causes clockwise moment? i) Is the rod in equilibrium? n e direction of 20 gf force is reversed. What is the magnitude of the resultant moment o the forces on the rod? (C) () Draw a diagram to show a block and tackle pulley system having marking the direction of load (L), effort (E) and tension (T). (ii) The pulley system drawn lifts a load of 150 N when mechanical advantage. ii) Is the above pulley system an ideal machine or an a velocity effort of60 N is ratio 3 applied. not? Find its 41 Question 9 A ray of light XY passes through a right angled isosceles prism as shown below. (a) ) What is the angle through which the incident ray deviates and emerges out of the prism? (i) Name the instrument where this action of prism is put into use. (ii) Which prism surface will behave as a mirror? (b) 3] An object AB is placed between O and Fj on the principle axis of converging lens as shown in the diagram. 2F2 LENS Copy the diagram and by using three standard rays starting from point A, obtain an image of the object AB. 3] (c) An () object the is placed position at a distance of 12 cm from a convex of the lens of focal image. (ii) nature of the image. Question 10 Draw (a) the diagram of a object. length 8 cm. Find [4) right angled isosceles prism which is used to erect the image of an [3] (b) Wooden Box A Sonometer O Paper rider Tuning 10 kg Fork A Tuning Fork B The diagram above shows a wire stretched over a sonometer. Stems of two tuning forks A and B are touched to the wooden box of the sonometer. It is observed that the paper rider (a small piece of paper folded at the center) present on the wire flies off when the stem of vibrating tuning fork B is touched to the wooden box but the paper just vibrates when the stem of vibrating tuning fork A is touched to the wooden box. (i) Name the phenomenon when the paper rider hust vibrates. (ii) Name the phenomenon when the paper rider flies off. (ii) Why does the paper rider fly off when stem of uning fork (c) B is touched to the box? (3] person is standing at the sea shore. An observer on the ship, which is anchored in between a vertical cliff and the person on the shore, fires a gun. The person on the shore hears to sounds, 2 seconds and 3 seconds after seeing the smoke of the fired gun. If the speed of sound in air is 320 ms* then calculate (i) the distance between the observer on the ship and the person on the shore. (i) the distance between the cliff and the observer on the ship. A CIM Man Observer Ship Sea shore Water 6
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