DC Motor Mechanics and Principles

The video explains the working principle of a DC motor, highlighting how a current-carrying conductor in a magnetic field experiences force, leading to rotation. It covers the basic construction of a DC motor, including the armature, commutator, and brushes. The application of Fleming's left hand rule is demonstrated to determine the direction of mechanical force. The video also discusses torque production and the mechanism of continuous rotation, even without a connected battery, by utilizing inertia and position changes.

What is the basic construction of a DC motor?

• A current-carrying armature connected directly to the battery.

• A rotating coil connected to an AC supply.

• A stationary coil connected to an AC supply.

• A current-carrying armature connected to the supply through commutator segments and brushes.

What happens when a current-carrying conductor is placed in a magnetic field?

• It stops conducting current.

• It experiences a mechanical force.

• It becomes magnetized.

• It generates heat.

In the elementary model of a DC motor, what is the direction of current in the left-side conductor?

• Inward

• Upward

• Outward

• Downward

How can the direction of mechanical force be determined in a DC motor?

• By measuring the voltage.

• By using the right-hand rule.

• By using Fleming's left-hand rule.

• By observing the rotation direction.

What does the thumb indicate in Fleming's left-hand rule?

• Direction of mechanical force.

• Direction of magnetic field.

• Direction of voltage.

• Direction of current.

What happens to the turn when it comes to a vertical position in respect to the magnetic field?

• The current decreases.

• The current increases.

• There is no current in the conductor.

• The conductor heats up.

What causes the turn to continue rotating even when there is no current?

• Friction.

• Magnetic force.

• Electrical resistance.

• Moment of inertia.

What is the direction of mechanical force on the conductor near the South Pole?

• Outward

• Downward

• Upward

• Inward

What is the direction of mechanical force on the conductor near the North Pole?

• Upward

• Downward

• Outward

• Inward

How does a practical DC motor differ from the elementary model?

• It has a stationary armature.

• It does not use commutator segments.

• It uses AC supply instead of DC.

• It has multiple turns on the armature coil and multiple poles.