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PHYSICS PAPER 1 (THEORY) Maximum Marks: 70 Time Allowed: Three hours (Candidates are allowed additional 15 minutes for only reading the paper. They must NOT start writing during this time). This paper is divided into four sections A, B, C and D. Answer all questions. Section A consists of one question having sub-parts of one mark each. Section B consists of seven questions of two marks each. Section C consists of nine questions of three marks each, and Section D consists of three questions of five marks each. Internal choices have been provided in two questions each in Section B, Section C and Section D. All working, including rough work, should be done on the same sheet as and adjacent to the rest of the answer. Answers to sub parts of the same question must be given in one place only. A list of useful physical constants is given at the end of this paper. A simple scientific calculator without a programmable memory may be used for calculations. SECTION A 14 MARKS Question 1: (A) In questions (i) to (vii) below, choose the correct alternative (a), (b), (c) or (d) for each of the questions given below: (i) Two point charges (+e) and (-e) are kept inside a large metallic cube without touching its sides. Electric flux emerging out of the cube is: (a) e / (c) - e / (d) Zero. (b) 2 e / (ii) In parallel combination of resistors: (a) current remains same (c) current and voltage both remains same (b) voltage remains same (d) none of the above. (iii) A circular coil carrying a current I has radius R and number of turns N. If all the three,i.e., the current I, radius R and number of turns N are doubled, then magnetic field at its centre becomes: (a) double (c) four times (b) half (d) one fourth. (iv) An object is kept on the principal axis of a concave mirror of focal length 10 cm, at a distance of 15 cm from its pole. The image formed by the mirror is: (a) virtual and magnified (c) real and magnified (b) vitual and diminished (d) real and diminished. (v) In Young s double slit experiment, sodium lamp is replaced by a blue light lamp. Then fringe width will become: (a) brighter (c) wider (increase) (b) fainter (d) narrower (decrease) (vi) Electric conduction in semiconductors is due to: (a) electrons (d) neither electrons nor holes. (b) holes (c) both electrons and holes
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