Working Principle of DC Motor (animation of elementary model)

Summary

The script explains the working principle of a DC motor, highlighting its simplicity. It describes the basic construction, including the armature, commutator, and brushes, and the interaction with a magnetic field. The video uses Fleming's left-hand rule to demonstrate how current-carrying conductors experience mechanical force, leading to rotation. It illustrates the process with a model and concludes by emphasizing the continuous rotation due to the changing positions of conductors and the magnetic field's interaction.

Takeaways

• 🔵 The working principle of a DC motor is based on the force experienced by a current-carrying conductor when placed in a magnetic field.
• 🔧 A basic DC motor consists of an armature, which is a current-carrying coil connected to a supply via a commutator and brushes, placed between the North and South poles of a magnet.
• 🔌 In a simple model, a single turn of a conductor is placed between two opposite poles, and when DC is supplied, the conductors experience a force due to the magnetic field.
• ➡️ Fleming's left-hand rule is used to determine the direction of the mechanical force acting on the conductors within the magnetic field.
• 🔃 The rotation of the armature produces a torque, causing the motor to rotate in a clockwise direction.
• 🔄 The commutator and brushes play a crucial role in reversing the current direction as the armature rotates, ensuring continuous rotation.
• 🔩 The motor's rotation continues due to inertia even when the current is momentarily interrupted as the brushes pass between commutator segments.
• 🔁 The process of current reversal and force application repeats as the armature continues to rotate, maintaining the motor's motion.
• 🏗️ In a more complex DC motor, multiple turns of wire are wound on a coil, and there are multiple poles instead of just two, enhancing the motor's efficiency and power.
• 📚 Understanding the working principle of a DC motor involves recognizing the interaction between electric current, magnetic fields, and mechanical motion.

Q & A

What is the basic principle behind the working of a DC motor?

The basic principle behind the working of a DC motor is that when a current-carrying conductor is placed in a magnetic field, it experiences a mechanical force. This force can be determined using Fleming's left-hand rule.

What are the main components of a DC motor?

The main components of a DC motor include a current-carrying armature, a commutator with segments, brushes, and a permanent or electromagnet with North and South poles.

How does the commutator play a role in the functioning of a DC motor?

The commutator in a DC motor helps to periodically reverse the direction of current in the armature coils as the motor rotates. This ensures that the force on the armature is always in the same direction, causing continuous rotation.

What is Fleming's left-hand rule and how is it used in a DC motor?

Fleming's left-hand rule is used to determine the direction of the force acting on a current-carrying conductor in a magnetic field. In a DC motor, it is applied to find the direction of mechanical force on the armature conductors, which helps in understanding the motor's rotation.

Why does the current direction in the armature change as the motor rotates?

The current direction in the armature changes due to the action of the commutator as the motor rotates. This change ensures that the mechanical force on the armature continues to act in the same direction, allowing the motor to maintain its rotation.

What happens when the armature reaches a vertical position with respect to the magnetic field?

When the armature reaches a vertical position with respect to the magnetic field, the conductors are aligned such that they are between the commutator segments, resulting in no current flow and thus no force acting on the conductors.

How does the motor continue to rotate after passing the vertical position?

Due to the moment of inertia, the motor continues to rotate past the vertical position. As the armature moves into a horizontal position again, the commutator and brushes reestablish current flow in the conductors, which now experience force due to their new positions in the magnetic field.

What is the purpose of having multiple turns in the armature of a DC motor?

Having multiple turns in the armature of a DC motor increases the total force and torque produced, which enhances the motor's ability to perform mechanical work.

How does the number of poles in a DC motor affect its performance?

The number of poles in a DC motor influences the motor's speed and torque characteristics. More poles generally result in smoother and slower rotation, while fewer poles can lead to faster but potentially less smooth operation.

What is the role of brushes in a DC motor?

Brushes in a DC motor make contact with the commutator segments to supply current to the armature coils. They play a crucial role in transferring electrical energy to the motor's rotating components.

Outlines

00:00

🔋 Understanding the Working Principle of a DC Motor

The paragraph explains the fundamental working principle of a DC motor. It begins with the basic concept that a current-carrying conductor experiences a force when placed in a magnetic field. The construction of a DC motor is described, highlighting the armature, commutator segments, and brushes. An elementary model is used to illustrate how a single turn of the conductor, when supplied with DC current, experiences mechanical force due to the magnetic field, causing rotation. Fleming's left-hand rule is introduced to determine the direction of this force. The paragraph also describes how the commutator switches the current flow as the armature rotates, ensuring continuous rotation in one direction. The explanation concludes with a demonstration of how the motor's rotation is sustained even when the conductor's position changes relative to the magnetic field.

05:01

🔄 Advanced DC Motor Construction and Operation

This paragraph extends the discussion to more complex DC motors, moving beyond the single-turn elementary model. It mentions that actual DC motors have multiple turns on a major coil and multiple poles instead of just two. The paragraph suggests that the same principles of force and rotation apply, but on a larger scale with more intricate construction. The video script ends with a call to action for viewers to subscribe, like, and comment, indicating that the content is intended to be educational and engaging.

Keywords

💡DC Motor

A DC motor is an electrical machine that converts direct current electrical energy into mechanical energy. The video script explains that the working principle of a DC motor is based on the interaction between a current-carrying conductor and a magnetic field, which results in a mechanical force. The script uses the DC motor as the central theme to explore how it operates, highlighting its components and the forces that drive its rotation.

💡Armature

The armature is a key component of a DC motor, typically a coil of wire that carries the electric current. In the script, it is described as being connected to the power supply and positioned between the North and South poles of a magnet. The armature's role is crucial as it experiences the force that leads to the motor's rotation, and the script illustrates this by discussing the flow of current through it.

💡Commutator

The commutator is a part of the DC motor that helps to periodically reverse the direction of current in the armature windings. This reversal is necessary to maintain the motor's rotation in one direction. The script mentions commutator segments and brushes, explaining how they work together to change the current direction, which is essential for the continuous rotation of the motor.

💡Magnetic Field

A magnetic field is a vector field that represents the magnetic influence of electric charges in motion. In the context of the video, the magnetic field is generated by the North and South poles of a magnet and interacts with the current in the armature to produce a mechanical force. The script describes how the direction of this force is determined by the orientation of the magnetic field and the direction of the current.

💡Fleming's Left Hand Rule

Fleming's Left Hand Rule is a mnemonic used to determine the direction of the force on a current-carrying conductor in a magnetic field. The script provides a detailed explanation of how to apply this rule with the left hand, using the thumb, forefinger, and second finger to represent the force, magnetic field, and current direction, respectively. This rule is central to understanding how the motor's force is generated.

💡Torque

Torque is the rotational force that causes an object to rotate around an axis. In the script, torque is produced due to the mechanical forces acting on the armature when current flows through it in the presence of a magnetic field. The video explains how these forces combine to create a torque that causes the motor to rotate in a clockwise direction.

💡Inertia

Inertia is the resistance of any physical object to a change in its state of motion. The script mentions inertia in the context of the motor's rotation, explaining that once the motor starts rotating, inertia allows it to continue rotating even when the current in the conductors is momentarily interrupted by the commutator.

💡Conductor

A conductor, in the context of the video, refers to the wire or path through which electric current flows. The script describes how a single turn of conductor is placed in the magnetic field and experiences a force when current flows through it. This force is what drives the rotation of the motor, and the script uses this concept to explain the basic working principle of a DC motor.

💡Poles

Poles, in the context of the video, refer to the magnetic poles of the magnet, typically labeled as North and South. The script explains that the armature is placed between these poles, and the interaction between the magnetic poles and the current in the conductors generates the force that causes the motor to rotate.

💡Rotation

Rotation is the circular movement of an object around a fixed axis. The script describes the rotation of the armature within the magnetic field as the motor operates. The continuous rotation is facilitated by the interaction between the magnetic field, the current, and the mechanical forces acting on the armature, as well as the role of the commutator in maintaining this rotation.

💡Electrical Supply

The electrical supply refers to the source of direct current (DC) that powers the motor. The script mentions that the armature is connected to the supply, which is essential for the flow of current through the conductors. The electrical supply is the driving force behind the motor's operation, and the script explains how it initiates the process that leads to mechanical motion.

Highlights

The working principle of a DC motor is based on the force experienced by a current-carrying conductor in a magnetic field.

A basic DC motor consists of an armature, commutator segments, and brushes, placed between the poles of a magnet.

In a simple model, a single turn of a conductor is placed between two opposite poles of a magnet.

The direction of mechanical force on the conductors can be determined using Fleming's left-hand rule.

When current flows through the conductors, they experience a mechanical force due to the magnetic field.

The forces on the conductors produce a torque that causes the armature to rotate.

The commutator and brushes ensure that the current direction changes as the armature rotates, maintaining the torque.

The rotation continues due to inertia when the conductors are momentarily not under the influence of the magnetic field.

As the armature rotates, the position of the conductors changes, altering the direction of the force acting on them.

Fleming's left-hand rule is applied again to determine the new direction of the mechanical force as the armature continues to rotate.

The continuous rotation of the armature is due to the alternating forces acting on the conductors near the poles.

In a real DC motor, multiple turns of wire are wound on the armature, and there are multiple poles.

The principle of rotation in a DC motor is the same as in the elementary model, but with more complexity.

The video explains the continuous rotation of a DC motor through the interaction of magnetic fields and electric current.

The video concludes by summarizing the key points and encourages viewers to subscribe, like, and comment.

Transcripts

working principle of DC motor working

principle of DC motor is very simple we

can see that when the current conductor

is placed in magnetic field it

experience some force in particularly

direction the very basic construction of

a DC motor contains a current carrying

armature which is connected to the

supply and through commutator segments

and brushes the armature is placed

between North and South Pole of a

permanent or an electromagnet in

elementary model one single turn of

conductor is placed between two opposite

poles if we start to supply DC via

commutator system current will start to

flow as we see positive terminal of a

battery is connected to left conductor

of a turn and negative terminal is

connected to right conductor of a turn

as we see in model North Pole of the

magnet is placed near left side and

South Pole is placed near right side of

the turn current and left-side flows

inward and current and right side flows

outward

as we see conductor is carrying current

and they placed in magnetic field both

of them experienced a mechanical force

acted on them direction of mechanical

force can be easily determined by

applying Fleming's left hand rule to do

this spread out your left thumb

forefinger and second finger so they are

all at 90 degrees to one another

[Music]

with that if the forefinger is a line a

long direction of magnetic field from

North Pole to the South Pole and second

finger is a line a long direction of the

current and left-side conductor then

thumb indicates direction of mechanical

force similarly if the forefinger is a

line a long direction of magnetic field

from North Pole to the South Pole and

second finger is a line a long direction

of the current and right-side conductor

then thumb indicates direction of

mechanical force due to this upward and

downward force is on the turn one torque

is produced when turn rotates on

clockwise direction as shown

[Music]

after rotation of the turn turn comes to

vertical position in respect of the

magnetic field at this position there is

no current in conductor because turn

conductor and brushes rest between two

calm mutators

[Music]

hence there is no force acting on

conductor by due to moment of inertia

turn continue to rotate and comes

horizontal again position of conductor

has been changed here that means

conductor which was previously in left

position comes to right position and

which was previously in right position

comes to left position at that position

we can determine mechanical force with

applying Fleming's left hand rule let's

do that to do this spread out your left

thumb forefinger and second finger so

they are all at 90 degrees to one to

another so if forefinger is a line in

direction of magnetic field that is from

North Pole to South Pole and second

fingers aligned in direction of a

current in the left-side conductor then

thumb indicates direction of mechanical

force this is clearly upward here

so if forefinger is a line in direction

of magnetic field that is from North

Pole to South Pole and second fingers

aligned in direction of the current in

the right-side conductor then fome

indicates direction of mechanical force

this is clearly downward here do this

upward and downward forces turn tends to

rotate in clockwise direction from that

explanation we can come to conclusion

that here in this model we can see that

whichever conductor comes near South

Pole experience upward mechanical force

and near north pole downward mechanical

force and do this continuously forces

mechanical turn rotate even if battery

is not connected particularly DC motor

rotates had the same principle like this

elementary model instead of single turn

and DC motor we have mountain turns on

major coil and instead of two poles

there is number of pole

installed I hope that you liked it

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