In elementary physics and electrical engineering, energy is commonly defined as the ability to do work or to produce observable effects. Which option best aligns with this definition?

Introduction:
Energy underpins all physical processes. In engineering contexts, energy can transform into different forms, creating effects such as heating, lighting, and acoustic vibrations. This question probes conceptual understanding of energy's manifestations.

Given Data / Assumptions:

• Standard textbook definition: energy is the capacity to do work or to produce heat.
• Real systems convert energy between forms (electrical, thermal, radiant, acoustic, mechanical).
• No specific numeric computation is required.

Concept / Approach:
If a system has energy and interacts with its environment, it can generate various measurable outcomes. Electrical energy can heat a resistor (Joule heating), power a lamp to emit light (radiant energy), or drive a loudspeaker to produce sound (mechanical/acoustic energy). Therefore, multiple listed effects are valid manifestations of energy.

Step-by-Step Reasoning:
1) Start from the broad definition: energy enables work or heat production.2) Map to effects: work/heat can appear as temperature rise, light emission, or mechanical vibrations.3) Recognize conversions: electrical → thermal (I^2 * R), electrical → radiant (LED filament), electrical → mechanical → acoustic (speaker).4) Therefore, any of the listed effects can result from energy expenditure.

Verification / Alternative check:
Conservation of energy guarantees that input energy equals the sum of outputs plus losses. Observing heat, light, or sound confirms energy transfer and conversion have occurred.

Why Other Options Are Wrong:
Produce heat, light, or sound (individually): each is correct but incomplete versus the comprehensive set.

None of these: contradicts the fundamental definition and common observations.

Common Pitfalls:
Equating energy solely with electrical energy, or forgetting that energy can neither be created nor destroyed but only converted. Real devices often produce multiple effects simultaneously (e.g., lamps also produce heat).

Final Answer:
All of the above