Time allowed : 3 hours
Maximum Marks : 70
General Instructions :

(i) All questions are compulsory.
(ii) Marks for each question are indicated against it.
(iii) Question number 1 to 8 are very short-answer questions each of 1 mark. Answer them in about one sentence each.
(iv) Question number 9 to 18 are short-answer questions of 2 marks. Answer them in not more than 30 words each.
(v) Question number 19 to 27 are short-answer questions of 3 marks. Answer them in not more than 50 words each.
(vi) Question number 28 to 30 are long-answer questions of 5 marks each. Answer to these questions should be around 150 words each.
(vii) Use Log Tables, if necessary.

Q1) Is the ratio of number of holes and the number of conduction electrons in a n-type extrinsic semiconductors more than, less than or equal to 1?  (Marks 1)

Q9) Use mirror formula to show that a convex mirror always produces a virtual image independent of the location of the object.  (Marks 2)

Q10) An astronomical telescope of magnifying power 10 consists of two thin lenses 55 cm apart. Calculate the focal lengths of the lenses.  (Marks 2)

Q11) An -particle and a proton are accelerated through same potential differences. Calculate ratio of linear momentum acquired by the two. 
(Marks 2)

Q19) Give the logic symbol & truth table for an OR gate. Explain with the help of a circuit diagram, how is this gate realized in practice.  (Marks 3)

Q20) Explain by drawing a labelled diagram, how a PNP transistor can be used as an amplifier in common base configuration.  (Marks 3)

Q21) A wire of uniform cross-section has a resistance of 9 . It is cut into three equal pieces. Each piece is stretched uniformly to three times its length and all the three stretched pieces are connected in parallel. Assuming that stretching of wires does not cause any change in density of their material, calculate total resistance of the combination described.  (Marks 3)

Q28) Distinguish between 'average value' and 'r.m.s. value' of an alternating current. A 60 V - 10 W electric lamp is to be run on 100 V - 60 Hz mains. (a) Calculate the inductance of choke coil required. (b) If a resistor is to be used in place of choke coil to achieve the same result, calculate its value. 
(Marks 5)