Which energy transformations occur in the sequence Mechanical → electrical → light?

• A. Electrical → light → mechanical
• B. Chemical → mechanical → electrical
• C. Mechanical → chemical → light
• D. Mechanical → electrical → light

Answer: (D)

When energy starts as mechanical and ends as light, the most natural path is机械 energy → electrical energy → light energy. A hand-cranked flashlight is a perfect example: turning the crank provides mechanical energy to spin a generator, which converts that motion into electrical energy, and then the lamp uses that electricity to emit light. The electrical form sits in the middle because the light source is driven by electricity.

Other sequences describe different setups or different starting points. They don’t fit the straightforward path from motion to illumination in a device designed to light up from motion, which is why this one best matches how such systems function.