Which describes an energy transformation from electrical energy to thermal energy?

• A. A bolt of lightning strikes a tree.
• B. A candle glows as it burns.
• C. A wave crashes against the shore.
• D. A flashlight uses a battery to operate.

Answer: (A)

Electrical energy can become heat when it encounters resistance or rapid energy release. A bolt of lightning does exactly that: the electrical energy of the discharge heats the surrounding air to extremely high temperatures, causing the air to rush outward and light to flash. The heat generated in the air is a direct conversion from electrical energy to thermal energy, with light and sound as additional byproducts of the same event.

The candle's energy starts as chemical energy in the wax, which is transformed into light and heat—not electrical energy. A wave crashing involves mechanical energy from motion and gravity, producing sound and some heat, but not from electrical energy. A flashlight uses electrical energy to produce mostly light, with heat as a smaller byproduct, so the main transformation isn’t primarily to heat.