CBSE Physics Sample Question Paper : Set-6
Q. 1. What is the approximate wavelength range for the visible spectrum?
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Q. 2. Why copper wire is not used in potentiometer?
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Q. 3. When the length of a microscope tube is increased how is its magnifying power affected?
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Q. 4. The curves show voltage current relationship for two photo cathodes illuminated by a single source. In what way the cathodes dif¬fer?
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Q. 5. A point charge is rotated in a circle of radius r around a charge q. What will be net work done?
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Q. 6. A 900 pF capacitor is charged by a 100 V battery. How much electrostatic energy is stored by the capacitor? .
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Q. 7. What is the direction of current at the cold junction of a copper-bismuth thermocouple?
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Q. 8. How do comets form tails?
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Q. 9. What are (i) terrestrial planets and (ii) jovial planets? Give one example of each.
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Q. 10. Suppose that the potential energy between electron and proton in hydrogen atom at a distance r is given by U = -ke2 /3r3.
(i) What is the force between them?
(ii) What is the radius of such an orbit?
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Q. 11. What is an electromagnetic wave? How an electromagnetic wave is possible in space?
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Q. 12. Calculate the frequency associated with a photon of energy 3.3x10-20 J. (h = 6.6x10-34 Js).
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Q. 13. Neutrons produced in fission can be slowed down even by using ordinary water. Then, why is heavy water used for this purpose?
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Q. 14. Calculate the luminous intensity of 200 W tungsten lamp whose efficiency is 18 Im/W. What are the assumptions?
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Q. 15. An electric dipole free to move is placed in a uniform electric field. Explain along with diagram its motion when it is placed (a) parallel to the field (b) perpendicular to the field.
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Q. 16. A capacitor is joined to a cell, a resistance R, an ammeter and a key when the key is pressed write the expression for the current in terms of resistance R capacitance C and e.m.f. e.
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Q. 17. Show, by drawing ray diagrams, how a totally reflecting glass prism can be used to deviate a ray of light through (i) 90° (ii) 180°.
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Q. 18. Give a diagram from which it is clear that “taller the antenna, longer the coverage of the television broadcast".
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Q. 19. State laws of photoelectric effect
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Q. 20. In J J. Thomson’s method, prove that the specific charge of an electron is given by the expression 1/r E/B2 where r is the radius of the circular path produced by electron in the region of magnetic field B and E the electric field applied.
(i) Give Huygens ‘Principle of secondary wavelets, (ii) Show graphical¬ly the intensity distribution in a single slit diffraction pattern.
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Q. 21. The critical angle for total internal reflection for saphire surrounded by air is 34.4°. Calculate the polarising angle for saphire if the light is incident from air.
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Q. 22. Define capacitance. Derive an expression for the capacitance of a parallel plate capacitor with vacuum.
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Q. 23. A circular conducting wire loop of radius r, with a current i is placed in a magnetic field perpendicular to its plane. Find the force on a small part dl of the conducting wire and the force of compression in the wire. When the magnetic field is switched off what happens to the radius of the loop?
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Q. 24. (i) What is electrolysis? (ii) How long will it take to deposit electrolytically 10.79 g of silver on the cathode of a silver voltmeter by a current of 25 A? (ece of silver = 0.001118 g/C).
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Q. 25. Explain how the masses of two stars belonging to a binary system can be determined?
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Q. 26. Show that the angle of minimum deviation produced by a thin prism is reduced to one-fourth (with respect to air) when it is immersed hi water. Given eng = 3/2 and enw = 4/3.
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Q. 27. (a) Show that the contact potential difference between two dissimilar metals is given by
φ = W1-W2 / e
where W1 and W2 are the work functions of the metals.
(b) The e.m.f of a zinc carbon cell is 1.5 volt, how much energy will a system have on dissolution of one zinc ion in a voltameter?
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Q. 28. State Lenz’s law. Show how Lenz’s law follows from the principle of conservation of energy?
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Q. 29. State and explain Faraday’s laws of electrolysis. Define electrochemical equivalent.
Doppler effect can help to decide whether a star is approaching or receding from the earth. Explain how?
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Q. 30. Describe Millikan’s oil drop experiment for determination of charge on an electron.
Drawa ray diagram to show the formation of image of an object placed between the pole and centre of curvature of a concave mirror. Derive the formula connecting object distance (u), image distance (v) and focal length (f) for this particular case for the given concave mirror. State clearly the assumption and sign convention used.
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