Class X - SSLC - Physics Quick Notes : 2 - Magnetic effect of electric current - 2

9. Important parts of electric motor:

• Field magnet
• Armature coil
• Graphite brushes
• Split ring commutator
• Split ring commutator helps to change the direction of current.

10. Determination of polarity of a current carrying solenoid:

• The end of the solenoid at which current llows in the clockwise direction will be the South Pole and the end at which current flows in the anticlockwise direction will be the North Pole.
• The end of the current carrying solenoid which repel the North pole of the magnet is the North Pole and the end of the solenoid which repel the South Pole of the magnet is the South Pole.

11. Motor Principle:

• A current carrying conductor in a magnetic field experiences a force
• Devices that work on the basis of motor principle:
  (i) Electric motor (ii) Moving coil loudspeaker

12. Energy conversion in motor and loud speaker:

• Electric motor: Electrical energy to Mechanical energy
• Moving coil loudspeaker: Electrical energy to Sound energy

13. Important parts of Moving coil loudspeaker:

• Field magnet
• Voice coil
• Diaphragm.

14. Working of moving coil loudspeaker:

• The electrical pulses from the microphone are strengthened and passed through the voice coil.
• Thus the voice coil placed in the magnetic field moves to and fro rapidly according the electric pulses.
• Thus the diaphragm vibrates and reproduces sound.

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