Energy conversion devices: which device converts mechanical energy into electrical energy under routine operation?

Introduction / Context:
Modern systems employ many transducers that convert one form of energy into another. Correctly identifying the direction of energy conversion is essential when selecting power sources or sensors. This question focuses on the classic electromechanical conversion used in power plants and portable generators.

Given Data / Assumptions:

• Normal operating conditions and conventional device definitions.
• No exotic or hybrid devices considered.
• Steady conversion from a mechanical prime mover to electricity.

Concept / Approach:
An electrical generator (dynamo or alternator) converts mechanical energy into electrical energy via electromagnetic induction: motion of conductors in magnetic fields induces an emf. The other listed devices convert non-mechanical energy (light, heat, chemical) to electricity or vice versa.

Step-by-Step Solution:
1) Identify the energy source: mechanical rotation, translation, or vibration.2) Apply Faraday’s law qualitatively: changing magnetic flux through a coil induces voltage.3) Conclude that the device intended for mechanical-to-electrical conversion is the generator.

Verification / Alternative check:
Power stations use turbines (steam, gas, water, wind) to spin alternators, directly demonstrating mechanical-to-electrical conversion at scale.

Why Other Options Are Wrong:

• Solar cell: Converts light (photons) to electricity.
• Thermocouple: Converts temperature difference to voltage (Seebeck effect).
• Chemical cell: Converts chemical energy to electricity.
• None of the above: Incorrect because generator is correct.

Common Pitfalls:
Confusing a motor with a generator; while many machines can work reversibly, the question asks for mechanical-to-electrical conversion, which is generator mode.

Final Answer:
generator.