1. Magnetic effect of electric current:
- A magnetic field is produced around a current carry ing conductor.
- The direction of magnetic field depends on the direction of current.
- The direction of magnetic field around a current carrying conductor be found by James Clerk Maxwell's Right Hand Thumb rule
2. Right hand thumb rule by James Clerk Maxwell:
- If a current carrying conductor is held in the right hand with the thumb towards the current then other fingers encircle in the direction of magnetic field.
3. Magnetic field around a circular coil carrying current:
- If the current is in clockwise direction, magnetic field is directed into the coil.
- If the current is in anticlockwise direction, magnetic field is directed out of the coil
4. Solenoid:
- A solenoid is an insulated wire wound in the shape of a helix.
- A current carrying solenoid act as a magnet
5. Differences between the magnetic fields of Solenoid and bar magnet:
- Bar magnet:
- Magnetism is permanent.
- Polarity' cannot be reversed
- Magnetic strength cannot be changed as desired
- Solenoid:
- Magnetism is temporary.
- Polarity can be reversed by reversing the current
- Magnetic strength can be increased or decreased as desired.
6. The factors affecting the magnetic effect of electricity:
- Strength of current
- Number of turns of the coil
7. Experiment to prove motor principle:
- A copper rod is suspended perpendicularly between die poles of a U magnet.
- When a current is passed, the copper rod moves in one direction.
- When (he current is reversed, the copper rod moves in the opposite direction
- The copper rod will move in the opposite direction if the magnetic field is reversed.
- The direction of motion of the conductor can be found by Fleming's Left Hand Rule
8. Fleming's Left Hand Rule:
- Hold the forefinger, middle finger and thumb of the Left I land in mutually perpendicular directions with forefinger towards the direction of magnetic field, middle finger towards the direction of current then thumb will indicate the direction of motion of the conductor.