CBSE Board Physics Question Paper -1998
Q. 1. In a medium, the force of attraction between two point electric charge distance d apart is F. What distance should these be kept apart in the same medium so that the force between them
becomes 3 F ?
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Q. 2. Name the experiment which established the quantum nature of electric charges.
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Q. 3. Draw the energy-band diagram for a p-type extrinsic semiconductor.
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Q. 4. An electron and proton moving with the same speed enter the same magnetic field region at right angles to the direction of the field. For which of the two particles will the radius of circular path be smaller ?
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Q. 5. Two electric bulbs A and B are marked 220 V, 60 W and 220 V, 100 W respectively. Which one of the two has greater resistance ?
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Q. 6. An ideal inductor is in turn put across 220 V, 50 Hz and 220 V, 100 Hz supplies. Will the current flowing through it in the two cases be the same or different ?
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Q. 7. Write the following radiations in an ascending order in respect of their frequencies. X-rays, micro-waves, ultra-violet rays and radiowaves.
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Q. 8. Write down the truth table for the following combination of gates :
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Q. 9. Two identical charges of charge Q are kept at a distance r from each other. A third point charge is placed on the line joining the above two charges such that all the three charges are in equilibrium. Calculate the magnitude and location of the third charge.
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Q. 10. When a capacitor is connected in series with a series L-R circuit, the alternating current flowing in the circuit increases. Explain why ?
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Q. 11. V-I graph for a metallic wire at two different temperatures T1 and T2 is as shown in the figure. Which of the two temperatures T1 and T2 is higher and why ?
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Q. 12. Explain the principle on which the working of a potentiometer is based. Why is the use of potentiometer preferred over that of a voltmeter for measurement of emf of the cell ?
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Q. 13. State the working principle of a tangent galvanometer. Write the mathematical expression for measuring current using the tangent galvanometer.
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Q. 14. You are given two identical looking bars A and B. One of these is a bar magnet and the other is an ordinary piece of iron. Give an experiment to identify which one of the two is a bar magnet. You are not to use any additional material for the experiment.
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Q. 15. Define the terms luminous flux and luminous intensity. How are these related to each other ?
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