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APEX ACADEMY ICSE PRE-BOARD EXAMINATION 2023-24 PHYSICS Maximum Marks: 80 Time Allowed: Two hours Candidates are allowed additional 15 minutes for only reading the paper. They must NOT start writing during this time. __________________________________________________________________________________________________ Section A is compulsory. Attempt any four questions from Section B The intended marks for questions or parts of questions are given in brackets [ ] __________________________________________________________________________________________________ SECTION A (40 MARKS) (Attempt all questions from this Section) Question 1 [15] Choose the correct answers to the questions from the given options. (Do not copy the questions, write the correct answers only) (i) The direction of clockwise moment is along the axis of rotation (a) inwards (b) outwards (c) either (a) or (b) (d) none of these (ii) A ray of light enters from medium A into medium B as shown. The refractive index of medium B relative to A will be: Medium B (a) greater than unity (b) less than unity (c) equal to unity (d) zero Medium A (iii) The radiation deviated the most in an electric field is : (a) alpha (b) beta (c) gamma (d) all (iv) How many joule of heat energy are required to raise the temperature of 500 g of copper from 26 to 126 ? Take c = 400 J kg-1 K-1. (a) 500 J (b) 5 kJ (c) 20 kJ (d) insufficient data (v) Which is more energetic? (a) alpha particle (b) beta particle (c) gamma rays (d) X-rays [1] [Turn over] V (volt) (vi) An electric fan and a heater are marked as 100 W- 220 V and 1000 W- 220 V respectively. The resistance of the heater is: (a) equal to that of the fan (b) less than that of the fan (c) greater than that of the fan (d) zero (vii) The shape of the magnetic field lines around a current carrying straight conductor is /are: (a) concentric circles (b) straight line (c) parabola (d) square (viii) The V-I graph of a conductor is as shown. Its resistance is : (a) 5/3 9 (b) 3/5 6 3 (c) 5/2 3 (d) 2/5 0 5 10 15 20 I (ampere) (ix) Characteristic of sound by which we can distinguish between two sounds of same loudness and pitch is known as (a) loudness (b) pitch (c) quality (d) intensity (x) If a machine is an ideal machine, then the ratio of mechanical advantage (MA) to the velocity ratio (VR) is: (a) greater than 1 (b) less than one (c) equal to one (d) can have any value (xi) A man does 800 J of work in lifting a 40 kg bucket from a well. The depth of the well is (Take g = 10 m s-2 ) (a) 1 m (b) 0.5 m (c) 200 cm (d) 0.2 m (xii) For given current I, the heat produced (H) in a wire is related to the resistance (R) as: (a) H R 1 (b) H (c) H R2 1 (d) H 2 (xiii) At the traffic signals, red light is used for due to the reason that it can be seen from a distance. The phenomenon involved is known as: [2] (a) Refraction (b) Reflection (c) Scattering (d) Dispersion (xiv) Resonance is a special case of: (a) natural vibration (b) free vibration (c) forced vibration (d) none of these (xv) The temperature required for the process of nuclear fusion is nearly: (a) 1000 K (b) 104 K (c) 105 K (d) 107 K Question 2 (i) (a) What is a fuse? (b) Name the material of fuse. (c) One characteristic of the material used for fuse. (ii) State the function of split rings in a d.c. motor. (iii) An electric bulb is rated 100 W- 250 V . What information does this convey? (iv) The ratio of amplitudes of two waves is 3 : 4. Find the ratio of their (a) loudness, and (b) pitch. (v) Figure shows the distance-displacement graph of two waves A and B. Compare (a) the amplitude (b) the wavelength of the two waves. (vi) Can the centre of gravity of a body be situated outside its material ? Give an example. (vii) What physical quantity does the electron volt (eV) measure? How is it related to the S.I. unit of that quantity? Question 3 (i) A single fixed fulley and a movable pulley both are separately used to lift a load of 50 kgf to the same height. Compare the efforts applied. (ii) Calculate the effective resistance between the points A and B in the network shown in figure. A B (iii) A nucleus is -radioactive. (a) Write the equation representing -decay. (b) What general name is given to the product nucleus with respect to ? (iv) What is critical angle ? (v) Write an expression for the magnifying power of a simple microscope. How can it be increased? [3] [3] [2] [2] [2] [2] [2] [2] [2] [2] [2] [2] [2] SECTION B (40 MARKS) (Answer any Four) Question 4 (i) State the factor that determines (a) the pitch of a note, (b) the loudness of the sound heard, and (c) the quality of the note. (ii) A cell of e.m.f. 2 V and internal resistance 1.2 is connected to an ammeter of resistance 0.8 and two resistors of 4.5 and 9 as shown in figure. Find: (a) the reading of the ammeter, (b) the potential difference across the terminals of the cell, and (c) the potential difference across the 4.5 resistor. [3] 1.2 0.8 (iii) (a) Draw a labelled diagram of a d.c. motor showings its main parts. (b) What do you mean by electromagnetic induction? Question 5 (i) (a) Radioactivity is a nuclear phenomenon. Why? (b) What is the name given to elements with same mass number and different atomic number? (ii) (a) A nucleus emits 2 particles and 1 particle to form a nucleus . Find the atomic number and mass number of X. (b) Calculate the amount of energy released due to a loss of mass of 1 kg. (iii) Calculate the mass of ice needed to cool 150 g of water contained in a calorimeter of mass 50 g at 32 such that the final temperature is 5 . Specific heat capacity of calorimeter = 0.4 J g-1 -1, specific heat capacity of water = 4.2 J g-1 -1, latent heat capacity of ice = 330 J g-1. Question 6 (i) A ray of light incident at an angle of incidence 480 on a prism of refracting angle 600 suffers minimum deviation. Calculate the minimum deviation. (ii) Draw a ray diagram to show how a converging lens is used as a magnifying glass to observe a small object. Mark on your diagram the foci of the lens and the position of the eye. (iii) In figure A, B, C and D are four pendulums suspended from the same elastic string XY. The lengths of pendulum A and D are equal, while Y X the length of pendulum B is shorter and of the pendulum C is longer. Pendulum A is set into vibration. (a) What is your observation about the vibration of B pendulum D ? (b) Give reason for your observation in part (a). D A (c) What type of vibrations take place in pendulum B and C ? C (d) Give reason for the answer in part (c). Question 7 (i) Where must an object be placed in front of a convex lens of focal length 20 cm to obtain a real and four times magnified image ? Where will the image form ? (ii) (a) Define couple. (b) State its effect. [4] [3] [4] [3] [3] [4] [3] [3] [4] [3] [3] (iii) (a) Draw a labelled diagram of a block and tackle system of pulley with two pulley in each block. [4] Including the direction of the load, effort and tension in the string. (b) Write down the relation between the load and the effort of the pulley system. Question 8 (i) A uniform metre rule balances horizontally on a knife edge placed at the 58 cm mark when a weight [3] of 20 gf is suspended from one end. (a) Draw a diagram of the arrangement. (b) What is the weight of the rule ? (ii) State the energy changes in the following cases while in use: [3] (a) washing machine (b) burnig coal (c) steam engine (iii) (a) Define the term angle of deviation. [4] (b) How does the angle of deviation produced by a prism change with increase in the angle of incidence. Draw a curve showing the variation in the angle of deviation with the angle of incidence at a prism Surface. Question 9 (i) (a) What is meant by scattering of light ? [3] (b) Give reason why the smoke from a fire looks white. (ii) A beam consisting of red, blue and yellow colours is incident normally on the face AB of an [3] isosceles right angled ABC as shown in figure. Complete the diagram A to show the refracted and the emergent rays. Given that the critical angle of glass-air interface for yellow colour RED + BLUE + YELLOW is 450. C (iii) Show how the energy of a freely falling object remains conserved. -------------------------------::----------------------------- [5] B [4]
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