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An electric fan motor is a crucial component found in most household fans. Its primary role is to convert electrical energy into mechanical energy, thereby causing the fan blades to rotate. This rotation circulates air, creating a cooling effect in the room.
A fan motor consists of several key parts:

• Stator: The stationary part that provides the magnetic field.
• Rotor: The rotating part that turns with the fan blades.
• Commutator: Assists in reversing the direction of current in the motor, ensuring smooth operation.

The motor operates based on the principle that an electric current flowing through a conductor in a magnetic field experiences a force. This force leads to rotation. While starting, the motor requires a high current to overcome inertia and get the fan blades moving. During operation, the fan stabilizes and draws less current, which is efficient and economical.

To understand how much current a fan motor uses, it involves calculating the initial and operating currents. When the fan starts, it draws a high current, known as the initial current. This is because the motor needs to overcome the inertia of the stationary blades.
Once the fan reaches its normal speed, it operates more efficiently and uses only a fraction of the initial current. In the original problem, the fan draws 15% of the initial current when it operates normally. This percentage indicates the efficiency and reduction in electrical consumption at steady operation.
To find the operating current, first determine the initial current. For many calculations, this is sometimes measured or provided. Once you have it, multiply by the percentage of running efficiency, in this case, 0.15 (representing 15%), to find the current at normal speed.

Ohm's Law is a fundamental principle in electronics and physics that relates voltage, current, and resistance in an electrical circuit. It is expressed by the equation:\[ V = I R \]where:

• \( V \): Voltage across the component (in volts).
• \( I \): Current flowing through the component (in amperes).
• \( R \): Resistance of the component (in ohms).

In the problem, this law helps calculate the initial conditions of the fan motor, where no back emf is present yet.
Ohm’s Law allows us to determine unknowns in a circuit if two of the three variables are known. It is particularly useful in analyzing circuits, ensuring components are used effectively, and avoiding overloading.

Electromotive Force (emf) is a measure of the energy that causes electrons to flow in a circuit, often described as "voltage." In motors, the term "back emf" becomes significant. It refers to the voltage generated by the motor itself when in operation.
When a fan motor spins at normal speeds, it acts like a generator, creating its own voltage in opposition to the supplied voltage. This phenomenon is why it's called "back" emf, as it acts against the input voltage. The back emf is crucial for reducing current consumption, providing efficiency at a higher operational speed.
In our original task, we calculate back emf to understand the efficiency of the motor during steady-state operation. Using the back emf formula, the calculated 102.0 V indicates that the motor is significantly resisting the initial supplied voltage of 120.0 V, thus efficiently operating with reduced current usage.