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_______________________________________________________________________________ PHYSICS SCIENCE Paper 1 (Two hours) 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. _______________________________________________________________________________ Section I is compulsory. Attempt any four questions from Section II. The intended marks for questions or parts of questions are given in brackets [ ]. _______________________________________________________________________________ SECTION I (40 Marks) Attempt all questions from this Section Question 1 a. How does the effect of force differ in the two following cases? [2] A force is applied on(i) a rigid body and (ii) non-rigid body. b. Whenever force is applied, will the work be done? Support your answer with an example. [2] c. Differentiate between ideal machine and actual machine. [2] d. State the transformation energy taking place [2] (i) washing machine. (ii) charging cell e. How fast should a man of mass 60 kg run so that his KE is750 J? [2] Question 2 a. Scissors for cutting cloth have blades much longer than the handles; but shears for cutting metals have short blades and long handles.Explain why? [2] b. Give two reasons why the efficiency of a single movable pulley system is not 100%. [2] c. A body of mass 50 kg has a momentum of 3000 kgm/s. Calculate the KE of the body. [2] 1 ICSE (Grade : X) | PHYSICS (SCIENCE Paper-I) | Pre Board Exam-1 d. To use a machine as a force multiplier, which class of lever should preferred? [2] Draw a sketch of such a lever. e. The position of the centre of gravity of a body remains unchanged even when the body is deformed. Comment the statement. [2] Question 3 a. State two advantages of using a right angled prism as reflector rather than a plane mirror. b. Can the light passing from air to water suffer total internal reflection? Why? [2] [2] c. State any two factors on which the angle of deviation depends. [2] d. Explain why the colour of sky is different during different time of a day. [2] e. The speed of light in a transparent medium is 0.6 times that of its speed in vacuum. What is the refractive index of the medium? [2] Question 4 a. Define one diopter. [2] b. Can the absolute refractive index of a medium be less than one? Support your answer. [2] c. (i) Write down an expression for in terms of angles i & r. [2] (ii) In above if r= 90 , what is corresponding i called. (iii) What is the physical significance of i as in the part (ii) above. d. When a white light passes through a prism produces dispersion of light but it does not happen when it is passes through a rectangular glass. Explain. e. Give one example of a body having constant speed, though acceleration is present. [2] [2] SECTION II (40 Marks) Attempt any four questions from this section Question 5 a. A uniform metre scale is kept in equilibrium when supported at the 60 cm mark and a mass M is suspended from the 90 cm mark. (i) Draw a diagram of the arrangement. 2 ICSE (Grade : X) | PHYSICS (SCIENCE Paper-I) | Pre Board Exam-1 [4] (ii) State with reason whether the weight of the scale is greater than, less than or equal to the weight of mass M. b. A cook uses a 'fire tong' of length 28 cm to lift a piece of burning coal of mass 250 g. [3] If he applies his effort at a distance of 7 cm from the fulcrum, what is the effort in S.I. unit? Take g = 10 m/s2. c. The thickness of a glass slab is 0.2 m and it is placed over a flat book, the refractive [3] index of the glass slab is 1.5. A student looks through it and finds that the normal shift is x, find x. Question 6 a. A block and tackle pulley system has a velocity ratio 3. [3] (i) Draw a labeled diagram of this system. In your diagram, indicate clearly the points of application and the directions of the load and effort. (ii) Why should the lower block of this pulley system be of negligible weight? b. A boy of mass 40 kg runs up a flight of 15 steps, each 15 cm high in 10 s. Find the work done and the power developed by him. Take g = 10 Nkg-1. c. A monochromatic point source of light O is seen through a rectangular glass block ABCD. Paths of two rays, in and outside the block, are shown in the figure below. O A B D (i) C Does the source 'O' appear to be nearer or farther with respect to the surface AB? 3 ICSE (Grade : X) | PHYSICS (SCIENCE Paper-I) | Pre Board Exam-1 [3] [4] (ii) How does the shift depend on the thickness (AD or BC) of the block? (iii) For the same rectangular glass block, which colour from the visible spectra will produce themaximum shift? Question 7 a. (i) Name the radiation which causes a rapid increase of mercury when it is focu on the bulb of a thermometer. Give reason. [3] (ii) How are the radiations above in (i) are detected? State one use of this radiation. b. Jewellers cut jewels so that total internal reflection is more likely. Two materials used in jewelery have different refractive indexes. The refractive index of Material A is 2.5 and the refractive index of Material B is 1.3. Explain why the rays of light inside Material a are more likely to be totally internally reflected than those in Material B. [3] c. There are four media A, B, C and D having refractive indices 1.33, 1.52, 1.44 and 1.65 respectively. In which of the four media the speed of light will be the maximum? Why? [2] d. A convex lens of focal length 25 cm and a concave lens of focal length 10 cm are placed in close contact with each other. Calculate the lens power of this combination. [2] Question 8 a. (i) State work energy theorem with suitable examples. [2] (ii) Prove theoretically that for a freely falling body the total mechanical energy is Constant [3] (iii) For the oscillation of a simple pendulum, state the position of the bob where its accelerationdue to gravity is maximum. [2] b. Draw a neat labeled ray diagram to show the real & apparent position of an air bubble that is trapped in a rectangular glass block when it is viewed from directly above. [3] Question 9 a. The sky appears black in the absence of atmosphere. Give scientific reason. b. (i) A boy uses a spectacle of focal length -60 cm. Name the defect of vision he is 4 ICSE (Grade : X) | PHYSICS (SCIENCE Paper-I) | Pre Board Exam-1 [2] suffering from. [4] (ii) Which lens is used for the correction of this defect? (iii) Compute the power of the lens. c. In figure below PP1 is the principal axis of a lens and AB and BC are the incident and refracted ray of the lens. [4] A C B P P1 (i) Copy the diagram and mark O as the optic centre of the lens. (ii) Identify the lens type and find the position of principal focus. (iii) Locate the position of the image formed. Question 10 a. Diagram alongside shows an object AB placed on the principal axis of a convex lens [4] placed in air. F1 and F2 are the two foci of the lens. (i)Draw a ray of light starting from B and passing through O. Show the same ray after refraction by the lens. (ii) Draw another ray from B which passes through F2 after refraction by the lens. (iii) Locate the final image formed. (iv) Is the image-real or virtual? B F1 A O F2 5 ICSE (Grade : X) | PHYSICS (SCIENCE Paper-I) | Pre Board Exam-1 (v) What will happen to the intensity of the image formed by the above lens when the half portion of the lens is covered with a black paper? [2] b. The diagram shows a point source of light S, a convex lens L and a plane mirror M. These are placed such that rays of light, from S return to it after reflection from M. [4] (i) What is the distance OS called? (ii) To which point (left of S, on S, or right of S) will the rays return, if M is moved to the left and brought in contact with L? Explain. L M O S 6 ICSE (Grade : X) | PHYSICS (SCIENCE Paper-I) | Pre Board Exam-1
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