Formatting page ...
THE CATHEDRAL AND JOHN CONNON SCHOOL PRELIMINARY EXAMINATION STD X Physics 2017-2018 DATE: 9/1/2018 TIME-2 hours MAX MARKS:80 SECTION 1 (40 MARKS) Attempt ALL questions in this section. Take g =10 N/kg wherever needed. Question 1. a. b. c. d. e. Two bodies of mass m1 and m2 have the same linear momentum. What is the ratio of their kinetic energies? [2] A train ls travelling on a level track at a speed of 72 km/hr. It is pulled by an engine which exerts force of 12,000 N. Calculate the power of the engine in kilowatt. [2] The moment of a force of 6N about a point is 3 Nm. Calculate the distance of the point of application of the force from the point. [2] What is the relationship between: (i) VR, Distance moved by load (d1) and the distance moved by the effort (d 2) (ii) VR, MA, and efficiency ( ) [2] How can he mechanical advantage of a lever be increased ? [2] Question 2 a. b. c. d. e. Explain the difference between optically denser medium and optically rare medium. [2] Name the color of light which is deviated (i) the most, (ii) the least, on passing through a prism. [2] (i) Name a natural phenomenon which is a result of the contrast between the specific heat capacities of land and water (ii) Give an example where water is used as a coolant [2] The wavelength of a normal wave is 66 m. Calculate the frequency of the wave, if the velocity of sound is 330m/s. Would this sound be audible to the human ear? [2] How do you tune your radio-set to a particular station? Name the phenomenon involved in doing so. [2] Question 3 a. b. c. d. e. Define resistance and resistivity. [2] A bulb is joined to a battery of e.m.f.6 V. A steady current of 0.5A flows through the circuit. Calculate the total energy provided by the battery in 5 minutes. [2] Write down a fission reaction [2] Write two properties of beta radiations [2] An alpha particle captures (i) one electron, (ii) two electrons. ln each case, what does it change to? [2] Question 4 a. b. c. d. Draw a displacement-time graph for damped vibrations. State 2 was by which the pitch of a stringed instrument can be lowered? State 2 differences between an electro-magnet and bar magnet. A hot solid of mass 60g at 100oC is placed in 100g of water at 18C. The final steady temperature recorded is 20oC. Find the specific heat capacity of the solid. [2] [2] [2] [2] e. A coin placed under a glass slab of refractive index 1.5 appears to be raised by 0.8 cm. Find the real thickness of the glass slab. [2] SECTION II (40 marks) Attempt any FOUR questions from this section Question 5 a. The door of a building is 4m broad. It can be opened by applying a force of 100 N at the middle of the door. Calculate the least force which can open the door. Where should it be applied? [3] b. What kind of energy is possessed by a body in each of the following cases. (i) A moving bullet (ii) A spinning top (iii) A stretched rubber string? [3] c. A block and tackle system of 5 pulleys is used to raise a load of 500N steadily through a height of 20 cm. The work done against friction is 2000J. Calculate (i) Work done by the effort (ii) Efficiency of the system (iii) Displacement of the effort applied (iv) M.A [4] Question 6 a. State 3 properties which are common to all electro-magnetic radiations [3] b. (i) What do you mean by absolute refractive index of a medium? (ii) Which lens can produce a real, inverted image? (iii) Which characteristic property of light is responsible for the blue color of sky? [3] c. A spherical lens is used in the collimator of a spectrometer. What type of les is used? Draw a neat, labelled diagram to illustrate it, State 2 characteristics of the image formed. [4] Question 7 a. A person standing between the 2 vertical cliffs and 800 m away from the nearest cliff, shouted. He heard the first echo after 5 s and the second echo 10 s later. Calculate: (i) the speed of sound in air (ii) the distance between the cliffs [3] b. If the highest note detectable by the human ear has a frequency of 20 kHz, find the shortest wavelength which the human ear can detect. Take velocity of sound as 330 m/s. Name the waves that have wavelengths shorter than this shortest detectable wavelength [3] c. A convex lens forms an image 16 cm long, of an object 4 cm long, kept at a distance 6 cm from the lens. The object and image are on the same side of the lens. (i) What is the nature of the image? (ii) Find the position of the image? (iii) Find the focal length of the lens. [4] Question 8 a. Draw a V-l graph for a conductor at two different temperatures. What conclusion do you draw from your graph for the variation of resistance of conductor with temperature? [3] b. What is Lenz s law? State 2 points of difference between a step-up transformer and step-down transformer. [3] c. (i) Which is thinner a 5 A fuse wire or a 20 A fuse wire? (ii) (iii) Explain why terminal voltage is less than the e.m.f. of cell Mention 2 factors on which the strength of an electro-magnet depends. [4] Question 9 a. A metallic piece of 500g of lead is melted in a crucible and it is observed that a 40 W electric heater will keep it in the liquid state at its melting point. If the heater is switched off, the temperature of the lead begins to fall after 5 minutes Calculate the specific latent heat of fusion of lead. [3] b. A certain mass of ice at 0oC is converted into steam at 100oC by constant heating. Draw a temperature-time graph showing the change in phases. [3] c. (i) Explain: The SH.C. of copper is 0.4 J/g K (ii) Are the boiling point and condensation point identical for a pure substance? (iii) Calculate the heat gained by 400g of water when it is heated from 10 c to 50 C Take SHC of water = 4200 J/ kg K [4] Question 10 a. State one use each of alpha, beta and gamma radiations emitted from radio isotopes. [3] b. (i) What is nuclear fusion? (ii) Give one example of a fusion reaction. (iii) What other name is given to nuclear fusion [3] c. A radiation sample is kept at the center of an evacuated spherical vessel. (i) Out of the types of radiations, name the radiations for which the vessel is (1) safe and (2) unsafe? Justify your answer (ii) Suggest a way for more safety. (iii) Does evacuated of the vessel help in safety? Why? [4]
|
