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F.M 80 Tim e 2 Hrs HALF-YEARLY 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 a) How much work is done by a coolie carrying a load on his head and moving on a frictionless horizontal surface. State reasons. [2] b) Fill in the blanks(Do not copy): (i) In a domestic electric circuit, the potential differences between the live and neutral wire is __________________. (ii) Resistors of 2 , 4 and 6 are connected in parallel combination. The ratio of potential difference across them is _____________. [2] c) Calculate the heat capacity of a metal block of mass 500g if 2000J of heat raises its temperature from 323K to 423K. [2] d) A radioactive substance is oxidized. What changes are expected to occur in its nature of radioactivity? Explain your answer. [2] e) A guitarist tightens the strings of the guitar before playing. What parameter is he changing? What subjective property of sound change with this? [2] Question 2 a) Give the energy transformations of the following: [2] (i) An arrow shot from a bow (ii) A microphone in use b) For the same angle of incidence, the angles of refraction in three different media A, B and C are 15O, 25O and 30O respectively. In which medium, the speed of light be minimum and why? [2] c) What is electron volt? How is it related to the SI unit of energy? [2] d) State the factors affecting loudness and pitch of a sound. [2] e) A uniform metal wire has resistance of 80 . It is cut into four equal lengths. Find the equivalent resistance when three parts are connected in series and fourth in parallel. [2] 1
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