An electric motor in a fan or machine converts which form of energy primarily into mechanical energy of rotation?

Introduction / Context:
Energy conversion is a central idea in physics and everyday technology. Electric motors are devices found in fans, pumps, mixers, washing machines and many other appliances. They take energy in one form and convert it into mechanical energy, usually rotational motion of a shaft. This question asks which initial energy form is converted by an electric motor into mechanical energy.

Given Data / Assumptions:

• An electric motor is used in common appliances such as fans and mixers.
• The output of the motor is mechanical energy in the form of rotation.
• The motor is powered by a standard electrical supply or battery.
• Other forms of energy such as chemical and sound may appear as side effects but are not the primary input.

Concept / Approach:
Electric motors operate on the principle that a current carrying conductor placed in a magnetic field experiences a mechanical force. When multiple coils are arranged correctly and supplied with electric current, they produce continuous rotation. The energy that drives this process is electrical energy supplied from a power source. Inside the motor, some of this electrical energy is converted into mechanical energy of rotation, while some is lost as heat and a little as sound. Chemical energy is stored in fuels or batteries and must first be converted to electrical energy (in batteries) or mechanical energy (in engines) before use.

Step-by-Step Solution:
Step 1: Identify what goes into an electric motor: a supply of electrical energy, either from mains or a battery. Step 2: Identify what comes out: mechanical rotation of the shaft, used to drive fans, pumps or wheels. Step 3: Recognise that the key physical principle is the force on a current carrying conductor in a magnetic field. Step 4: As current flows through the motor windings, magnetic forces act on them and produce torque on the rotor. Step 5: This torque performs work and delivers mechanical energy to any connected load. Step 6: Therefore, the primary energy conversion is from electrical energy to mechanical energy.

Verification / Alternative check:
If the electrical supply to a motor is cut off, the motor quickly slows and stops, showing that it depends on continuous electrical input to sustain mechanical output. Technical specifications for motors always rate them in terms of electrical input power (watts or kilowatts) and mechanical output power. This confirms that the primary energy form entering the device is electrical.

Why Other Options Are Wrong:
Sound energy: Motors make some sound as a by product of vibration and air movement, but sound is not the energy input; it is a minor output.

Mechanical energy: Mechanical energy is the output, not the input, of a motor. An engine driven generator, by contrast, converts mechanical energy into electrical energy.

Chemical energy: Batteries store chemical energy and convert it to electrical energy, which then powers the motor; the motor itself takes electrical energy as input.

Common Pitfalls:
A frequent confusion occurs between batteries and motors; students sometimes say motors convert chemical to mechanical energy, skipping the intermediate electrical step inside the battery. It helps to think in terms of separate devices in an energy chain: chemical energy in fuel or battery to electrical energy in circuits, and then electrical energy to mechanical energy in the motor.

Final Answer:
An electric motor primarily converts electrical energy into mechanical energy.