CBSE Guess > Papers > Important Questions > Class XII > 2007 > Physics > Physics (Magnetism And Magnetic Effect Of Current) By: Mr. Abhishek Gupta

Magnetism And Magnetic Effect Of Current

Q. 1. Give 4 basic properties of magnets

Q. 2. What are magnetic lines of forces. Give 5 properties. In which one do they differ from electric lines of forces?

Q. 3. State coulomb’s law in magnetism and give the value, units and dimensions of μo

Q. 4. Derive the value of magnetic field intensity at an equatorial point of a bar magnet.

Q. 5. What is magnetic dipole moment. A magnet having dipole moment M is placed in a uniform magnetic field B. Derive the formula for torque acting on it.

Q. 6. Write short notes on

1. Cause of earth’s magnetism
2. Magnetic elements
3. Neutral points
4. Oersted’s experiment

Q. 7. What is tangent law in magnetism. Describe the construction and working of the tangent galvanometer.

Q. 8. State Biot-Savart law and using it derive the magnetic field strength at the center of a current carrying loop.

Q. 9. State Ampere’s circuital law. Using this derive the value of magnetic field at a distance R from a long straight current carrying wire.

(b) Using Ampere’s law, derive the value of magnetic field in a solenoid having n turns per unit length.

(c) Using Ampere’s law, derive the value of magnetic field in a toroid

Q. 10. Define the following terms and give their units

1. Magnetic field
2. Magnetic flux
3. Lorentz force

Q. 11. A proton moving with a velocity of 100m/s enters a region of magnetic field at an angle of 90o . Find the force acting on this proton due to the field. Using a proper figure show the path of the proton in the magnetic field.

Q. 12. A wire carrying current I is placed in a magnetic field B. Derive the value of force acting on this wire.

Q. 13. A straight horizontal conducting rod of length 2m and mass 5Kg is suspended by 2 vertical wires at its ends. A current of 10A is flowing in the rod. What magnetic field should be set-up in the nearby region so that the tension in the wires become zero.

Q. 14. Derive the value of force b/w 2 parallel conductors carrying current. When is this force attractive and when is it repulsive. Hence define an Ampere.

Q. 15. Derive the formula for the torque acting on a current carrying square coil placed in a magnetic field.

Q. 16. Find the magnetic moment of hydrogen atom.

Q. 17. Describe the construction and working of the moving coil galvanometer. How can it be made more sensitive.

Q. 18. A circular coil of 30 turns and radius 10cm carrying a current of 5A is suspended vertically in a uniform horizontal magnetic field of 100G. The field lines make an angle of 60o with the normal to the coil. Find the torque acting on this coil. Would the answer change if instead of the circular coil , we had a square coil but with the same area?

Q. 19. An alpha particle and a proton are accelerated by the same potential difference of 50V and enter a magnetic field of 100T perpendicular to their velocity. What kind of path will they trace in the magnetic field. Find the ratio of their radius and time period

Q. 20. Describe the construction and working of a cyclotron. Also derive the necessary relations.

Q. 21. Give 5 points of difference b/w paramagnetic and diamagnetic substances

Q. 22. Explain the domain theory of magnetism using a suitable figure. What is curie law?

Q. 23. Define the following terms

1. Hysterisis
2. Retentivity
3. Coercivity
4. Intensity of magnetization
5. Magnetic susceptibility

Q. 24. What happens to the magnetic moment if a bar magnet is cut

1. Transverse to its length
2. Along its length

Q. 25. Find the magnetic field at the center of the Circle of radius 2m, if 5A current is flowing in the Direction shown. The wire is assumed to be very long.

Q. 26. A rectangular ( 10cm x 5cm ) and having 1000 turns with a current of 2A is placed in a uniform magnetic field of 100 Gauss directed along the positive x axis. Due to the magnetic field a torque will act on it. Under what conditions will this torque be maximum and when will it be minimum.

Q. 27. An electron enters a region of magnetic field. Will it experience a force? “Under what conditions can this force be maximum and when will it be zero.

Q. 28. Two concentric coils A and B having radius 2m and 1m lie in the same plane. The coil A carries a current of 5A in the clockwise direction and the coil B carries a current 6A in the anti clockwise direction. Find the magnetic field induction produced at the common center.

Q. 29. What kind of materials are used for making

1. Transformer cores
2. Electromagnets
3. Permanent magnets
   Explain with proper reasoning

Q. 30. A square loop of side 1m and carrying 5A current is placed 2m away from a very long conductor carrying current of 10A. What is the net force on the loop due to the current carrying wire