A television set changes electrical energy to sound and light energy. In this process, some energy is

lost

Explanation:

When a television set changes electrical energy to sound and light energy, some of the initial energy is lost in other forms usually heat.

Energy conversion or transformation from one form to another is not an 100% efficient process. This is compliance with the law of thermodynamics.

The process of transforming energy brings about some loss of energy into the environment. No system is 100% efficient in transforming all the energy input into it. Some of the energy is usually lost in the process of conversion.