Final answer:
The incorrect statement about energy conversion devices is that Total Energy Input equals Useful Energy Output, as this does not account for energy lost to the surroundings, mainly as heat due to inefficiencies like friction. Efficiency is the ratio of useful energy output to the total energy input and is always less than 100 percent. So the correct option is a.
Step-by-step explanation:
The statement that is NOT true about energy conversion devices is option a: Total Energy Input = Useful Energy Output. This is not true because, in any energy conversion process, some energy is lost to the surroundings, often in the form of heat due to friction or other inefficiencies. The correct relationship can be expressed as Total Energy Input = Useful Energy Output + Energy Dissipated to the surroundings, which is the third law of thermodynamics stating that energy is conserved in an energy conversion process.
The efficiency (Eff) of an energy conversion device is defined as the ratio of useful energy output to the total energy input, which can be mathematically expressed as Efficiency (Eff) = (Useful Energy Output) / (Total Energy Input). This efficiency is always less than 100 percent in real-world applications since some energy is always lost as heat to the environment.