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प्रश्न
Explain the construction and working of an electric motor.
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उत्तर
1) Armature coil: A large number of turns of insulated copper wire wound on the iron core in rectangular a shape forms an armature coil ABCD as shown in figure
2) Strong magnet: The armature coil is placed in between two pole pieces (N and S) of a strong magnet. This provides a strong magnetic field
3) Split ring commutator: It consists of two halves (R1 and R2) of a metallic ring. The ends of the
armature coil are connected to these rings. Commutator reverses the direction of current in the armature coil.
4) Brushes: Two carbon brushes B1 and B2 are used to press the commutator.
5) Battery: The battery supplies the current to the armature coil.
Working of the electric motor:
When current is passed through the coil ABCD, arms AB and CD experience force. According to Fleming’s left-hand rule, the force experienced by arm AB is in the downward direction and arm CD in the upward direction. Both these forces are equal and opposite. This force rotates the coil in the anticlockwise direction until the coil is vertical. At this position, the contact between commutator and brushes break. So the supply to the coil is cut off. Thus no force acts on the coil. But the coil does not stop due to inertia. It goes on rotating until the commutator again comes in contact with the brushes B1 and B2. Again, the current starts passing through the coil and the arm AB rotates through 90°, 180°, 270° and 360 degrees. Now the force acting on arm AB is upward and arm CD is downward. Again this force moves the coil in the anticlockwise direction.
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संबंधित प्रश्न
What is the role of the split ring in an electric motor?
Name some devices in which electric motors are used
Explain the function of the following parts of an electric motor.
Split ring
Electric motor works on the magnetic effect of electric current.
State whether the following statement is true or false:
An electric motor converts mechanical energy into electrical energy.
Name the device which is used to reverse the direction of current in the coil of a motor?
What is the other name of the split ring used in an electric motor?
What is the function of a commutator in an electric motor made ?
Of what substance are the brushes of an electric motor made?
Of what substance is the core of the coil of an electric motor made?
What is the principle of an electric motor?
In a d.c. motor, why must the current to the coil be reversed twice during each rotation?
State what would happen to the direction of rotation of a motor if:
both current and magnetic field were reversed simultaneously.
What is an electric motor? With the help of a labelled diagram, describe the working of a simple electric motor
In an electric motor, the direction of current in the coil changes once in each:
two rotations
one rotation
half rotation
one-four rotation
An electric motor is a device which transforms:
mechanical energy to electrical
heat energy to electrical energy
electrical energy to heat energy only
electrical energy to mechanical energy
Tell the odd one out. Give proper explanation.
Loud speaker, Microphone, Electric motor, Magnet.
Which device is used to produce electricity? Describe with a neat diagram.
Study the following principle and answer the question.
A force is excreted on the current carrying conductor. The direction of this force depends on both the direction of the current and the direction of the magnetic field. This force is maximum when the direction of current is perpendicular to the direction of the magnetic field.
a) By which law we can determine the direction of force excreted on the current carrying conductor.
b) In which electrical equipment this principle is used.
c) Draw a diagram representing construction of this equipment.
d) Write the working of this equipment in brief.
Electric motors are devices that convert electrical energy into mechanical energy.
Observe the figure and write the answers to the questions asked.
- The construction shown in the figure is of which device?
- Explain the principle on which this device works.
- Write any three uses of this device.
Which of the following converts electrical energy into mechanical energy?
An electric motor converts ______.
State whether true or false. If false, correct the statement.
A generator converts mechanical energy into electrical energy.
State whether true or false. If false, correct the statement.
The speed of rotation of an electric motor can be increased by decreasing the area of the coil.
List the main parts of an electric motor.
In an electric motor, to make the coil rotating continuously in the same direction, the current is reversed in the coil after every half rotation by a device called ____________.
Commercial electric motors do not use ____________.
How can the speed of rotation of a coil be increased? Write at least three methods.
The most suitable material for making permanent magnets is ______.
The moving part of an electric motor is called ______.
Observe the following diagram and answer the questions.
- Construction of which equipment does the above diagram show?
- On which principle does this equipment work?
- According to which law the coil ABCD rotates?
- Write the law in your own words.
- Where is this equipment used?
