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Edusmart Tutorials Std: X IC Date: 26.12.24 Preliminary Examination Marks: 80 Duration: 2 hr Section A Q.1. Choose the correct answers to the questions from the given options: [15] (i) The turning effect produced in a rigid body around a fixed point by the application of force is called: (a) turning force (b) moment of force (c) moment of couple (d) none of these (ii) Which is the correct expression for potential energy? (a) mga (b) mgh (c) 1/2mgh (d) mgv (iii) Which of the following has centre of gravity outside the body? (a) a triangular lamina (b) a hollow cylinder (c) an L-shaped body (d) a circular lamina (iv) S.I unit of work is joule. It is expressed in terms of mass, length and time as (a) kgm s-3 (b) kgm3/s (c) kg m /s (d) kg m /s (v) A single fixed pulley is used because (a) its efficiency is 100% (b) it multiplies effort (d) it changes the direction of effort applied (c) it multiplies speed (vi) Amount of heat energy required to melt a given mass of a substance at its melting point without any rise in temperature is called (a) heat capacity (b) sp. heat capacity (c) latent heat of fusion (d) sp. latent heat of fusion (vii) A glass half filled with water is held above eye level when its top surface appears silvery. The above phenomenon is due to (a) reflection of light (b) refraction of light (c) total internal reflection of light (d) dispersion of light (viii) A mixture of red and green light is passed through a triangular prism such that they disperse. Dispersion takes place because in glass (a) Red light travels faster than green light (b) Green light travels faster than red light (c) Green light and red light travel at same speed (d) none of these (ix) An object is held 5 cm in front of a convex lens of focal length 8 cm. Its image is (a) virtual, erect and enlarged (b) virtual, diminished and erect (c) real, diminished and erect (d) virtual, enlarged and inverted (x) A string stretched between two nails is plucked in the middle. The vibrations produced in the string are (a) forced vibrations (b) free vibrations (c) damped vibrations (d) resonant vibrations (xi) A graph between V/I for a conductor is a straight line. The slope of the graph represents (a) resistivity of conductor (b) resistance of conductor (c) electrical power of conductor (d) electric work done by conductor (xii) In a parallel circuit (a) p.d at the ends of all resistors is same (b) current flowing through all resistors is same (c) the equivalent resistance of all resistors is more than any individual resistors (d) both (b) and (c) (xiii) Which can cause severe genetic disorders? (a) alpha radiation (b) beta radiation (c) gamma radiation (d) all of these (xiv) A wire carrying current is held over freely suspended magnetic needle, such that the current in the wire flows from South to North. The direction in which the north end of a freely suspended needle will point towards (a) west (b) east (c) north (d) south (xv)The important source background radiation is (a) radio waves emitted by cell phone towers (c) The radiations(cosmic) coming from deep space (b) decay of radio-active materials (d) Both (b) and (c) Q.2 (i) (a) Name the factors affecting moment of force? (b) If the moment of force is assigned a positive sign, the tendency of turning force be clockwise or anticlockwise. (c) Which of the following remain constant in a uniform circular motion: speed or velocity? (ii) (a) Where is the centre of gravity of uniform ring situated? (b) The position of centre of gravity remains unchanged even when the body is deformed. State whether the statement is true or false. (iii) (a) A ball is placed on a compressed spring. When the spring is released, the ball is observed to fly away. i. What form of energy does the compressed spring possess? ii. Why does the ball fly away? [3] [2] [2] (iv) (a) How does an ideal machine differ from practical machine? [2] (b) Can a simple machine can act as a force multiplier and speed multiplier at the same time? (v) Explain why water is used in hot water bottles for fomentation and also as a universal coolant. [2] (vi) A coin placed at the bottom of a beaker appears to be raised by 4.0 cm. If the refractive index of water is 4/3, find the depth of the water in the beaker. [2] (vii) (a) A ray of light passes from water to air. How does speed of light change? (b) Which colour of light travels fastest in air? [2] Q.3 (i) An objective placed in between F1 and 2F1 of a convex lens as shown in diagram. [2] Copy the diagram and using three rays starting from point A, Obtain the image formed by lens. (ii) Which characteristic of sound will change, if there is a change in: (a) its amplitude (b) in its waveform [2] (iii) A certain nucleus X has a mass number 14 and atomic number 6. The nucleus X changes [2] to Y with a mass number 14 and atomic number 7 after the loss of a particle. (a) Name the particle emitted. (b) Represent this change in the form of an equation. (iv) Calculate the equivalent resistance between points P and Q. (v) Why is fuse always placed in the live wire? [2] [2] Section B (Attempt any four questions) Q.4 (i) A ray of light incident at angle of incidence 'i' passes through an equilateral glass prism, such that the refracted rays inside the prism is parallel to the base of prism and emerges from the prism at an angle of emergence 'e'? (a) how is the angle of incidence 'i' is related to angle of emergence 'e'? (b) what can you say about the value of angle of deviation in such a situation? (ii) Ray of light is incident on the hypotenuse of a right-angled prism ABC as shown in diagram. (a) Copy the diagram and complete the path of ray PQ, till emerges from prism. (b) What is the value of angle of deviation for this prism? (c) Name the instrument where this action of prism is used. (iii) Converging lens is placed at a distance of 8 cm from a converging lens of focal length 10 cm. (a) State the nature, size and position of the image. (b) Can this image be taken on the screen? If not why? Q.5 (i) A ray of monochromatic light is incident from air on a glass slab: (a) Draw a labelled ray diagram showing the change in the path of the ray till it emerges from the glass slab. (b) Name the two rays that are parallel to each other. (c) Mark the lateral displacement in your diagram. (d) Name one factor that affects the lateral displacement of light as it passes through a rectangular glass block. (ii) (a) Where should an object be placed so that a real and inverted image of same size as object is obtained using a convex lens? (b) Draw a ray diagram to show the formation of image as specified in ii(a). (iii) (a) What do you understand by the term Critical Angle? (b) Name two factors which determines the critical angle for a pair of media. Q.6 (i) Radioactive nucleus undergoes series of decays according to sequence X X1 X2 X3. Atomic mass number and atomic number of X3 are 172 and 69 the respectively, what is the mass number and atomic number of X? (ii) (a) A man standing between two cliff produces a sound and hears two successive echos at intervals of 3 seconds and 4 seconds respectively. Speed of sound is 330 m/s, what is distance between two cliffs? (b) Will an echo be heard when distance between source of sound and reflecting surface is 10 m? Why? (iii) The diagram alongside shows a displacement-time graph for a vibrating body: (a) Name the type of vibrations produced by a body. (b) Give one example of a body producing such vibrations. (c) Why is the amplitude of wave gradually decreasing? (d) What will happen to vibrations of body after some time? Q.7 (i) A uniform metre scale can be balanced at the 70.0 cm mark when a mass of 0.05 kg is hung from the 94.0 cm mark. Draw a diagram of the arrangement and find the mass of the metre scale. (ii) Calculate the change in kinetic energy of a moving body, if its velocity is reduced to 1/3 of initial velocity. (iii A block and tackle system has V.R. = 5. (a) Draw a neat labelled diagram of a system indicating the direction of its load and effort. (b) Rohan exerts a pull of 150 kgf. What is the maximum load he can raise with this pulley system if its efficiency = 75%? Q.8 (i) (a) State one advantage of connecting electrical appliances in parallel combination. (b) What characteristics should a fuse wire have? (c) Which wire in power circuit is connected to the metallic body of an appliance? (ii) The diagram alongside shows a dual control switch circuit connected to a bulb. (a) Copy the diagram and complete so that the bulb is switched on. (b) Out of A and B, which one is live wire and which one is neutral wire? (c) Which of the cables, one rated 5 A and the other rated 15 A will be of thicker wire? Give a reason for your answer. (iii) An electric oven is marked 100 W-200V. Calculate: (a) resistance of its element. (b) energy consumed by oven in joules in 1/2 hour. (c) time in which it will consume 15kWh energy. Q.9 (i) How does a magnetic field setup by a solenoid change when: (a) number of turns in it are increased? (b) diameter of solenoid is reduced? (c) strength of current in solenoid is increased? (d) A soft iron core is placed inside the solenoid? (ii) 40 g of ice at 0 C is used to bring down the temperature of a certain mass of water at 60 C to 10 C. Find the mass of water used. [Specific heat capacity of water = 4200 J kg 1 C 1] [Specific latent heat of fusion of ice = 336 103 J kg 1] (iii) The diagram below shows the core of a transformer and its input and output connections: (a) State the material needed for the core (b) Copy and complete the diagram of the transformer by drawing input and output coils
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