Based on the concept of Energy Conversion Efficiency, which of the following statements is correct?

Statement 1: The efficiency (η) of an energy device is the ratio of useful work done to the total energy used.
Statement 2: The energy wasted in a device is given by the equation (1 - η)E.
Statement 3: The efficiency of lighting devices is measured in terms of efficacy, which is the ratio of the amount of light produced to power consumed.
Statement 4: In an ideal energy device, η = 0, meaning no energy is converted into useful work.