Which of the following best describes the function of an electric motor?
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A. Converts stored potential energy into mechanical energy
B. Converts mechanical energy into electrical energy
C. Converts electric energy into mechanical energy
D. Converts the voltage of an alternating current source
The Correct Answer and Explanation is:
The correct answer is:
C. Converts electric energy into mechanical energy.
Explanation:
An electric motor is a device designed to convert electrical energy (typically from an electric current) into mechanical energy. This transformation occurs through electromagnetic principles, utilizing the interaction between magnetic fields and electric current.
The basic operation of an electric motor can be explained through the following steps:
- Electric Current in the Motor: When an electric current passes through a wire, it generates a magnetic field around it. In an electric motor, this wire is typically wound into coils that are placed within a magnetic field, usually produced by a permanent magnet or an electromagnet.
- Magnetic Interaction: According to Faraday’s Law of Induction and Lorentz Force Law, when a current-carrying conductor (like the coil) is placed in a magnetic field, a force is exerted on the conductor. The direction of this force is perpendicular to both the direction of the current and the magnetic field, causing the coil (and the shaft it is attached to) to rotate.
- Mechanical Work: This rotation of the coil or armature produces mechanical motion, which is the desired outcome of an electric motor. This motion can then be used to perform a variety of tasks, such as turning a fan blade, driving a conveyor belt, or powering an electric vehicle.
Why Other Options Are Incorrect:
- A. Converts stored potential energy into mechanical energy: This description is more applicable to devices like springs or gravitational systems, not electric motors. Electric motors convert electrical energy, not potential energy.
- B. Converts mechanical energy into electrical energy: This describes a generator, which is the opposite of a motor. Generators convert mechanical energy into electrical energy.
- D. Converts the voltage of an alternating current source: This option is partially true but incomplete. While an electric motor may use alternating current (AC), the main function is to convert the electric energy into mechanical energy, not just adjust or modify voltage.
Thus, the defining function of an electric motor is the conversion of electric energy into mechanical energy, making C the correct answer.