Formatting page ...
Section A [2*5*4=40] Question 1 (a) State where acceleration due to gravity will be loweri. At an altitude 1200 km from Earth s surface or on Earth s surface ii. On Earth s surface or at a depth of 8 km from Earth s surface (b) i. Why are lorries provided with a steering wheel of diameter larger than that of cars? ii. Name the type of equilibrium in the case of an aeroplane moving at a constant height. (c) i. The work done by Jupiter in revolving the moon is zero though it follows an elliptical and not circular orbit. Justify. ii. State the energy conversion when water flows from a height of 34 m onto a turbine. (d) Give the characteristics of a good source of energy. (e) i. A staircase can be said to be a simple machine. Justify. ii. State two ways by which efficiency of a block and tackle system can be increased. Question 2 (a) The sound of a train s horn is heard much louder at night than at daytime in a silent atmosphere. Give two reasons. (b) i. A ray of light incident at the first surface of a glass prism suffers ___ and ___. ii. The type of glass which produces greater deviation of light rays is ___ (crown/flint). (c) An electromagnetic wave has a wavelength of 100 pm. i. Name the part of spectrum to which it belongs. ii. State one use of the wave. (d) You are provided with four resistances-1 , 2 , 3 and 6 . How will you connect them to obtain an effective resistance of 3 ? Also draw a diagram. (e) Why does a concave lens always form a diminshed image? State two other characteristics of an image formed by it. Question 3 (a) i. Why are cylindrical magnets used in electric generators? ii. State two ways of increasing the magnitude of e.m.f induced in secondary coil of a transformer. (b) Which material is used as a core in- (i) Electric bell (ii) Direct current generator? Give reasons for its use in the respective devices. (c) State the salient features of ring topology of household wiring. (d) i. How does temperature of electrolyte affect its terminal voltage? ii. How does temperature of a substance affect its refractive index? (e) State the objective property ofi. Sound related to its pitch ii. Light related to its colour Question 4 (a) State two ways of increasing rate of thermionic emission in a cathode ray tube. (b) Name the radiations which are (i) transmitted, (ii) absorbed, by greenhouse gases present in the atmosphere. (c) i. Give the technical name for the kind of switch used for staircase lamps and mains respectively. ii. Name the radiation produced when cathode rays strike a block of tungsten. (d) Calculate the electric bill for a house for the month of April: the house uses five 80 W fans for 6 hours, six 40 W bulbs for 5 hours, a 1000 W heater for 1 hour and a 800 W A.C. for 2 hours on daily basis. (e) A 500 W kettle can melt and increase the temperature of 0.5 kg of a solid of specific latent heat 50000 J kg-1 to 10 C in 1 minute 15 seconds. Calculate specific heat capacity of liquid. Section B Question 5 (a) i. A uniform metre rule of mass 80 g is pivoted on 78 cm mark and a weight of 50 gf is suspended from 100 cm mark of the rule. Where a weight of 20 gf should be suspended to make the rule horizontal? ii. State why it is necessary that in a gear system that linear distance along circumference of wheel for each tooth must be same for both gears. When is a gear system of gear ratio 1 used? [3] (b) i. A pulley system having 3 pulleys has velocity ratio 4. Draw a diagram of the system. ii. Differentiate single fixed and movable pulleys on the basis of utility and effect of weight of pulley on mechanical advantage. [3] (c) i. Give the energy conversions in- (i) Steam engine (ii) Chemiluminescence ii. Name and define the unit in which work function of a metal is expressed. iii. Water falling from a height of 15 m at a steady rate of 2 tonnes in a minute is used to drive a turbine in a hydroelectric power station. Considering overall efficiency of 45%, find the power output of the power station. [4] Question 6 (a) i. Name the lens used to produce an upright and magnified image. Also give a practical application of the same. ii. Draw a ray diagram to show the image formation by the lens. [3] (b) In a diagram locate 2 prisms and draw necessary angles for producing the deviation as given: [3] (c) i. Explain how sky is blue when viewed from Earth while Earth is blue when viewed from space. ii. Explain two factors on which shift in position of an object depends. [4] Question 7 (a) There are four test tubes A, B, C and D each of length 20 cm. A, B, C and D have water up to a level of 18 cm, 14 cm, 16 cm and 10 cm respectively. When an excited tuning fork is brought above A, a loud sound is heard. i. Name and define the phenomenon in A. ii. State the observations with B, C and D. Also give reasons. [3] (b) i. Electromagnetic waves are called so although they are unaffected by electric and magnetic fields. Explain. ii. We can distinguish sounds from a piano and a violin even when they are of same loudness and pitch. Explain. [3] (c) A pendulum is vibrating with a time period of 0.8 s. A gun is fired between two cliffs and successively echoes are heard after the pendulum has completed 5 and 10 oscillations respectively. If speed of sound in air is 320 m/s, find the distance between the cliffs and time after which an echo is heard from other cliff after a gun is fired from one cliff. [4] Question 8 (a) i. Label A, B and C. Why is C thicker and longer than A and B? ii. To which wire is the fuse always connected? Why? (b) i. Explain what you observe when the magnet is moved towards the coil (centre zero galvanometer). ii. Name and state the law used. [3] (c) Calculate the effective resistance and current in the circuit. [3] [4] Question 9 (a) With the help of a heating curve graph illustrate the changes in temperature with time when ice is converted to steam. [3] (b) i. In mountains pressure cooker is generally used for cooking. Explain why. ii. Specific latent heat of vapourisation of water is greater than specific latent heat of melting of ice. Why? iii. Why is water chosen to be circulated in black painted pipes in a solar concentrator? [3] (c) i. What would be the effect of mixing 20 g of water at 0 C with 10 g of ice at -5 C? ii. Calculate the time required to change 50 g of ice at -15 C to steam at 145 C with a heater of power 135 W. Specific heat capacity of ice=2.1 J/g/K, water=4.2 J/g/K, steam=2 J/g/K. Specific latent heat of fusion of ice=336 J/g, Specific latent heat of vapourisation of steam=2268 J/g [4] Question 10 (a) i. State what effect increasing the accelerating potential on the anodes has in a cathode ray tube. ii. Name the substances which can be used in the fluorescent screen. iii. State how temperature of metal affects thermionic emission. [3] (b) A type of transformer is used in mobiles and night lamps. i. Name the type of transformer ii. Which coil-primary or secondary-is made thicker and why? iii. What does the said transformer do? [3] (c) i. An element X of atomic number 90 and mass number 234 emits an alpha particle then a beta particle and comes to the ground state by emitting gamma radiation. Represent the changes with equations. ii. State the precautions for handling radioactive materials and nuclear waste. [4]
|
