DC Motor

DC motor is widely  used in most of the electronic equipments. Invention of DC motor makes life simple and faster.Maximum toys are made from DC motor. Did you play with DC motor?

Lets try to understand how it works.

Principal:

DC motor is based on

  1. It converts electrical energy into mechanical energy.
  2. When current carrying conductor placed in a magnetic field it experience force. Similarly if a rectangular current carrying loop is placed in a magnetic field it experience a torque. Couple of forces acting on a body having equal in magnitude and opposite in direction are called torque.

Construction:              

DC motor consists of a rectangular coil PQRS Consist of number of turns of insulated copper wires wound on a rectangular loop. Create magnetic field with a help of strong bar magnets. We  also use electromagnet to increase magnitude of magnetic field. Place loop in a magnetic field such that the arms PQ and RS are perpendicular to magneticfield and the arms QR and SP are  parallel to the magnetic field respectively.

Connect a battery to the end of rectangular loop by key k.Use commutator to alter the connection of battery. Thee arrangement is as shown in figure.

Working:

Tap to on the key. The direction of current is  fromP- Q- R -S in a rectangular loop as as shown in figure.

When current pass through the loop, each branch experience a force and the direction of force isgiven by Fleming’s left hand rule.

  1. Forbranch PQ : of magnetic field lines from north to south and the direction of flowing current from P to Q thus the force acting on this branch isin upward direction.
  2. For branch RS: The force acting on branch RS is downward because the direction of current is from R to S.
  3. For branch QR: The direction of current through branch QR and direction of magnetic field are same hence there is no force acting on this branch.
  4. For branch SP: The angle between flow of current through branch SP and magnetic field lines is 180 degree so  the resultant force banishes.

So the force is acting on branch PQ and RS only. The magnitude of force is equal but direction is opposite so loop will try to rotate clockwise. When rectangular loop completes half rotation then we can alter the connection with the help of commutator. This time the branch RS experience the force in upward direction and branch PQ experience force in downward direction result continuous rotation of rectangular loop.

Uses: DC motor is used in most of the equipments.

  • Electric fans.
  • Refrigerators.
  • Television.
  • Water pump.
  • Computers
  • CD players.
  • Washing machine.

Q) Answer the following questions.

1) What will be change in dc motor if rectangular loop is replace by circular loop?

2) What are the applications of DC motor?

3) List out the electronic equipment with continue DC motor.

Updated: April 23, 2021 — 1:11 am

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