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SMT. SULOCHANADEVI SINGHANIA SCHOOL, THANE SECOND PRELIM PHYSICS QUESTION PAPER TIME ALLOWED 2 HOURS MAXIMUM MARKS 80 SECTION I (40 MARKS) ATTEMPT ALL QUESTIONS FROM THIS SECTION Question 1[2x5=10] a) State the work- energy theorem. b) Give two points of difference between uniform circular motion and uniform linear motion. c) Draw a schematic diagram of a lever whose mechanical advantage is always less than one. d) Define the term: second focal point of a lens. e) Why is it more economical to transmit electrical energy at high voltage and low current? Question 2[2x5=10] a) Define total internal reflection. b) Give two points of difference between a step- up transformer and a step- down transformer. c) What is meant by green house effect? d) Draw a neat circuit diagram showing the use of dual control switches to light a staircase electric lamp. e) A bus and a car are moving on a horizontal road with the same kinetic energy. They are brought to rest by the application of brakes which provide equal retarding forces. Which of these will come to rest in a shorter distance? Justify. Question 3[2x5=10] a) How will the lateral displacement of a light ray be affected if: i. The thickness of the rectangular block is reduced. ii. Angle of incidence is increased. b) A nucleus contains no electrons, but it can emit them .How? 1 c) Why is the switch always connected in the live wire of the circuit? d) State the direction of rotation of driving and driven gears when the two gears makei. External contact ii. Internal contact. e) State two factors on which the resistance of a conductor depends. Question 4[2x5=10] a) Fill in the blanks: i. The direction of induced current in an AC generator can be determined by_______________. ii. For a given height h ,__________________ the length l of the inclined plane, lesser will be the effort required. b) Give one similarity and one difference between X-rays and gamma rays. c) In an electric bell what will happen if a steel rod is used in place of the soft iron armature? d) The notes of a sitar and a guitar sound different even if they have the same loudness and pitch. Why? e) Give two reasons as to why copper is preferred over other metals for making calorimeters. SECTION 2 (40 MARKS) ATTEMPT ANY 4 QUESTIONS FROM THIS SECTION Question 5- a) A parallel beam of light falls on a convex lens of focal length 18cm and comes out as a parallel beam from a second convex lens of focal length 12cm. Draw a ray diagram to show the arrangement of the lenses. How far apart are the lenses kept? [3] b) Find the total resistance of the circuit drawn below and the current drawn from the battery. [3] 2 c) Prove that mechanical energy is conserved when a body falls freely from a height h above the ground. Neglect air resistance [4] Question 6a) i). Explain why a tuning fork has two prongs. ii) What is meant by reverberations? [3] b) A family uses 8 bulbs of 60W each for 6 hours every day and 4 fans of 60W each for 12 hours every day when connected to 200V mains. Calculatei. Monthly bill (April) if energy costs Rs 2 per kWh ii. Minimum fuse rating [3] c) An object 2cm high is placed 8 cm away from a convex lens of focal length 24cm. Determine the nature, size and position of the image with the help of a scale diagram. [4] Question 7a) i). State the energy changes in the following, while in use:- Solar cell and Loud speaker ii.) State one advantage of AC over DC [3] b) i). A 12V battery has a capacity of 80A of current for one hour. How long can the battery keep a 60W bulb on? [3] ii) How can the melting point of ice be reduced from 00 to - 0 C? c) A pulley system can lift a load of 1200N by an effort of 250N. If the resistance due to weight of movable parts and friction is 300N, calculatei. Mechanical advantage. ii. Velocity ratio iii. Total number of pulleys in the system iv. Efficiency of the system. [4] 3 Question 8a) i).On a hot summer day, the water in a swimming pool remains comfortably cool .Give reasons. ii). State the SI units of: heat capacity and latent heat of fusion. [3] b) A man standing in front of a large wall claps once. He hears the echo after 1.5s. He moves 170m closer to the wall and claps again. This time he hears the echo after 0.5s. Calculate i.)The speed of sound in air ii) His distance from the wall at first [3] c) Draw a neat and labeled diagram of a hot cathode ray tube. [4] Question 9a) i) Why are household connections made in parallel? Give two reasons. ii) Two wires of the same material and same area of cross-section have lengths in the ratio1:5.Compare their specific conductance. [3] b) i) State two advantages of the ring system of house wiring. ii) At what voltage and frequency is electric power generated at the power generating station. [3] c) Copy the diagram given below. Draw the paths of the rays P, Q, R and S after they reach the surface (glass) and come out in air. (critical angle for glass with respect to air = 0 ) [4] 4 Question 10a) i). State whether a magnetic field is associated or not with- i) a static charge ii) a moving charge. ii) Explain why a 1kg weight kept on a glass sheet does not break it, while a 10g weight falling over it cracks the glass [3]. b) A radioactive substance emits particles, electric field as shown below: particles and rays which enter an i) Copy the diagram and draw the paths of , , ii) Which of the paths will remain the same if the direction of electric field is reversed? [3] c) A metal piece of mass 1kg is taken out from a furnace and dropped in 4kg of water due to which the temperature of water increases from 0 C to 0 C . The water is contained in a vessel of mass 0.5kg formed of the same metal as the metal piece. If the specific heat capacity of metal is 0.1kilocalorie /kg K ,calculate the temperature of the furnace.(specific heat capacity of water=1kilocalorie/kg K) [4] 5 6
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