Formatting page ...
F.M 80 Tim e 2 Hrs PRE-BOARD-II EXAMINATION 2018-2019 SUBJECT: Physics (SCIENCE Paper 1) CLASS- X Answers to this Paper must be written on the paper provided separately. You will not be allowed to write during the first 15 minutes. This time is to be spent in reading the Question Paper. The time given at the head of this Paper is the time allowed for writing the answers. Section I is compulsory. Attempt any four questions from Section II. The intended marks for questions or parts of questions are given in brackets [ ]. SECTION I (40 Marks) Attempt all questions from this Section. Question 1 [2 x 5 = 10] a) A wasp of mass 20g flies vertically up at a speed of 50cm/sec. What is the power in its wings? b) What energy conversions take place in the following, when they are working: i) Electric toaster ii) Microphone c) To use a machine as a force multiplier, what type (class) of lever should preferably be used? Draw a sketch of such a lever. d) Differentiate between infra-red rays and ultra-violet rays in terms of their: i) action on photographic plate ii) uses e) The particles of mud fly off tangentially from the wheel of a moving vehicle. Why? Question 2 [2 x 5 = 10] a) Critical angle for glass-air pair is 42 . What do you mean by this statement? b) Write the factors on which focal length of a lens depends. c) An object is placed in front of a lens between its optical center and the focus and forms a virtual, erect and diminished image. i) Name the lens which formed this image ii) Draw a ray diagram for the above formation of image. d) The refractive index of diamond is 2.42. What is meant by this statement? e) i) How is the refractive index of a medium related to its real depth and apparent depth? ii) Which characteristic property of light is responsible for the blue colour of the sky? Question 3 [2 x 5 = 10] a) A radar is able to detect the reflected waves from an enemy s aeroplane after a time interval of 0.02 milliseconds. If the velocity of the waves is 3 x 10 8 ms-1, calculate the distance of the plane from the radar. 1
|
