CBSE Physics Model Question Paper- III
1. What gate has the symbol shown in figure?
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2. What is non-ohmic resistance? Give one example.
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3. Define lumen.
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4. Define virtual value of current.
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5. What is the difference between focus and principal focus?
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6. What should be the properties of the material which should be used to make electromagnet?
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7. If a point charge q is rotated in a circle of radius r, what will be the work done when it has completed 2.5 rotations.
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8. What is difference between P.D. and e.m.f. of a cell?
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9. Show that the electric intensity is always perpendicular to the equipotential surfaces.
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10. What is drift velocity? How it is connected to current? Derive the relation, for the current in terms of drift velocity.
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11. How can you get a NOT gate by combination of NAND gates?
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12. Write down binary number of (583)10.
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13. What is nuclear holocaust?
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14. Why moving coil galvanometer is preferred over moving magnet galvanometer? (five two important reasons).
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15. What are meteorites? .
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16. Define magnifying power of an Astronomical telescope when final image of a distant object is formed at least distance of distinct vision. Write down its value?
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17. Deduce an expression for electric intensity due to a line charge.
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18. Using Ampere’s circutal law, deduce magnetic field at the centre of a toroid due to current flowing in it.
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19. Deduce Ohm’s law and from its relation, number out the factors upon which the resistance of a conductor depends.
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20. What is half life period and average life period? Define disintegration constant. Given half life period of radium to be 1600 year and you have only one atom of radium. When will it disinte¬grate?
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21. A current entres a Wheatstone’s bridge consisting of P = Ω == R = 10 Ω and S = 11Ω. What is the current through galvanometer if its resistance is 100 Ω?
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22. What is Gauss theorem? Deduce electric intensity at a point outside, on and inside a spherical shell.
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23. A circuit contains L, C and R. Deduce the phase relationship between E and I.
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24. What are elements of earth’s magnetic field? How do these help us to get knowledge of earth field?
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25. An electron is accelerated. through a P.D. of 1000 V and directed into space between two parallel plates separated by 0 02 m with a P.D. of 100 V between them. If the electrons enter perpendicular to the electric field between the plates, what magnetic field perpendicular to both electron path and electric field will be necessary so that the electron may travel in a straight line?
Take e = 1.6 x 10-19 C and m = 9 x 10-31 kg.
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26. What is polarisation of light? What can be concluded towards the nature of light from it? What is Brewster’s law and what important conclusion is drawn from it?
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27. How can junction diode be used as full wave rectifier?
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28. On the basis of Bohr’s atomic model, derive relationship for radii of Bohr’s orbit and explain hydrogen spectra.
A needle placed 45 cm from a lens forms an image on the screen 90 cm on the other side of the lens. Find its focal length. What is the type of lens? If needle is 5 cm long, what is the length of the image?
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29. What is magnifying power and resolving power of a microscope. Derive relationship for magnifying power of microscope.
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30. How can the field intensity on axial line of an electric dipole be deduced? How does the equation get modified for small dipoles? In what unit electric dipole moment measured?
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