Final answer:
The principle that energy cannot be created or destroyed, but can only change form, is called the law of conservation of energy, aligning with the first law of thermodynamics.
Step-by-step explanation:
The principle stating that energy cannot be created or destroyed, only changed, is known as the law of conservation of energy. This fundamental concept is also a key component of the first law of thermodynamics, which applies to both chemical and physical changes. For instance, light bulbs transform electrical energy into light and heat energy, and plants convert sunlight into chemical energy stored within organic molecules. No matter how energy is converted, such as from quarters to dollar bills or via cash and credit cards, the total amount remains unchanged, mirroring the constancy of money in financial transactions.