Which of the following best describes the energy changes which take place when a steam engine drives a generator which lights a lamp?

Analysis

To solve this problem, we need to trace the energy transformation chain starting from the source of power (the steam engine) to the final output (the lamp).

Concept Explanation

Energy transformation follows the Law of Conservation of Energy, which states that energy cannot be created or destroyed, only converted from one form to another. We look at the process in stages:

1. Steam Engine: A steam engine works by burning fuel to produce heat, which turns water into steam. The pressure of the steam is then used to move pistons or turbines, creating Kinetic Energy (mechanical energy).
2. Generator: The generator uses the kinetic energy from the engine to rotate coils within a magnetic field, converting that mechanical motion into Electrical Energy.
3. Lamp: The lamp receives the electrical energy and converts it into Heat (thermal energy) and Light (radiant energy).

Step-by-Step Solution

• Step 1: The process begins with the burning of fuel, which provides Heat.
• Step 2: This heat energy is used to move the engine, resulting in Kinetic Energy.
• Step 3: The generator converts the kinetic energy into Electricity.
• Step 4: The lamp consumes the electricity and produces Heat and Light.

Following this sequence: Heat → Kinetic → Electricity → Heat and Light.

Identifying the Answer

Comparing our sequence to the given options:

• Option A is incorrect because it misses electricity.
• Option B is incorrect because it starts with kinetic energy instead of heat.
• Option C matches our derived sequence perfectly.
• Option D is incorrect because it starts with electricity.

Exam Tip

When dealing with "Energy Transformation" questions, always identify the input and the output first. If you see a "generator," remember it always converts Kinetic (mechanical) energy into Electrical energy. If you see a "motor," it does the reverse (Electrical to Kinetic).