What is the definition of law of conservation of energy

The law of conservation of energy states that energy can neither be created nor destroyed - only converted from one form of energy to another. This means that a system always has the same amount of energy, unless it's added from the outside. This is particularly confusing in the case of non-conservative forces, where energy is converted from mechanical energy into thermal energy, but the overall energy does remain the same. The only way to use energy is to transform energy from one form to another.

Explanation:

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means that energy can neither be created nor destroyed; rather, it can only be transformed or transferred from one form to another.

Explanation: this is a shorter answer.

snell's law

refractve index = sin incidence / sin refraction