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CBSE CLASS XII

Physics

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  1. Show mathematically that potential at a point on the equatorial line of an electric dipole is zero
  2. A storage battery of emf 12 V and internal resistance 0.5 Ω is to be charged by a 120 V d.c. supply of negligible internal resistance. What resistance is required in the circuit for the charging current to be 3 A ? What is the terminal voltage of the battery during charging?
  3. Using Ampere circuital law derive an expression for the magnetic field along the axis of a torodial solenoid
  4. Derive the expression for the self-inductance of a solenoid.
  5. In a given circuit inductor L and resister R have identical resistance. Two similar electric lamps B1 and B2 are connected as shown. When switch S is closed,
    1. which one of the lamps lights up earlier
    2. will the lamps be equally bright after some time? Justify your answer.
  6. Define one coulomb of charge.
  7. The small ozone layer on the top of the stratosphere is crucial for human survival, why?
  8. Why can’t a transformer be used to step up dc voltage?
  9. What is the nature of the magnetic field in a moving coil galvanometer?
  10. The current is set up in a long copper pipe. Is there a magnetic field
    1. inside
    2. outside the pipe?
  11. Sketch three equipotential surfaces for a pt. charge.
  12. How is the coulomb force between two charges affected by the presence of the third charge?
  13. What is the cause of induced emf?
  14. Why are microwaves used in RADAR?
  15. A uniform magnetic field gets modified as shown below, When two specimens X and Y are placed in it.
    16. dentify the two specimens X and Y
  16. State  the reason for the behaviour of the field lines in X and Y.
  17. Give any one difference between FAX and e-mail systems of communication.
  18. Give the ratio of the number of holes and number of conduction electrons in an intrinsic semiconductor.
  19. How does focal length of a lens change when red light is replaced by blue light?
  20. How does the intensity of central maximum change, if the width of the slit is halved in a single slit diffraction experiment?
  21. How will the photoelectric current change on decreasing the wavelength of incident radiation for a given photosensitive material?
  22. In which series of hydrogen spectra, the transitions involve the longest changes energy?
  23. What is the mass of pion plus (p+)?
  24. Vehicles moving in foggy weather use yellow colour head-lights. Why?
  25. Name the physical quantity whose S.I. unit is :
  26. Coulomb Per Volt
  27. Volt/ meter.

 

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Submitted By : Mr. Raghu Sharma
Email: [email protected]