Explain the process of electric motor?
Answers
Answer:
An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of rotation of a shaft. Electric motors can be powered by direct current (DC) sources, such as from batteries, motor vehicles or rectifiers, or by alternating current (AC) sources, such as a power grid, inverters or electrical generators. An electric generator is mechanically identical to an electric motor, but operates in the reverse direction, converting mechanical energy into electrical energy.
Electric motors may be classified by considerations such as power source type, internal construction, application and type of motion output. In addition to AC versus DC types, motors may be brushed or brushless, may be of various phase (see single-phase, two-phase, or three-phase), and may be either air-cooled or liquid-cooled. General-purpose motors with standard dimensions and characteristics provide convenient mechanical power for industrial use. The largest electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors are found in industrial fans, blowers and pumps, machine tools, household appliances, power tools and disk drives. Small motors may be found in electric watches.
In certain applications, such as in regenerative braking with traction motors, electric motors can be used in reverse as generators to recover energy that might otherwise be lost as heat and friction.
Electric motors produce linear or rotary force (torque) intended to propel some external mechanism, such as a fan or an elevator. An electric motor is generally designed for continuous rotation, or for linear movement over a significant distance compared to its size. Magnetic solenoids produce significant mechanical force, but over an operating distance comparable to their size. Transducers such as loudspeakers and microphones convert between electrical current and mechanical force to reproduce signals such as speech. When compared with common internal combustion engines (ICEs), electric motors are lightweight, physically smaller, provide more power output, are mechanically simpler and cheaper to build, while providing instant and consistent torque at any speed, with more responsiveness, higher overall efficiency and lower heat generation. However, electric motors are not as convenient or common as ICEs in mobile applications (i.e. cars and buses) as they require a large and expensive battery, while ICEs require a relatively small fuel tank.
Answer:
In electric motor the electrical energy changes into mechanical energy.
Electric Motor
Electric motor is a device that converts electrical energy to mechanical energy.
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Parts of a Electric Motor
Insulated Copper wire: A rectangular coil of wire ABCD
Magnet Poles: A magnet as placed above ie North Pole and South Pole. This creates a magnetic field as shown above.
Split Rings: Two disjoint C-shaped rings P and Q. It acts as a commutator (which can reverse the direction of current)
Axle: The split rings are placed on the axle which can rotate freely.
Brushes: The outside of the split rings are connected to conducting brushes X and Y.
Source Battery: To source current.
Working
When the current begins to flow, current flows through brush X, then A to B, B to C, C to D and then to brush Y and into the battery.
Now applying Fleming's Left Hand Rule to wire AB, Current is along AB, Magnetic Field is as shown (North-> South), the motion of the wire is downwards.
Now applying Fleming's Left Hand Rule to wire CD, Current is along CD, Magnetic Field is as shown (North-> South), the motion of the wire is upwards.
The rectangular coil begins to move in the anti-clockwise direction
Note that during anti-clockwise motion, the split rings and axle also move, whereas the brushes don't move.
After half a rotation, Wire CD and Split ring Q moves to the left. Wire AB and Split ring P moves to right. Brushes X and Y donot move.
Now applying Fleming's Left Hand Rule to wire CD, Current is along DC. (Battery -> Split ring Q -> DC , Magnetic Field is as shown (North-> South), the motion of the wire is downwards.
Now applying Fleming's Left Hand Rule to wire AB, Current is along BA. (Battery -> Split ring Q -> DC --> CB -> BA --> Split ring P) , Magnetic Field is as shown (North-> South), the motion of the wire is upwards.
So, again the coil rotates in the anti-clockwise direction.
The reversal of current in the coil results in the continous rotation of the coil. The reversal of current is achieved by the commutator rings
Applications
Electric Fans
Refrigerators
Mixers
Washing machines