What is light effect? Examples of luminous efficiency of conventional (commonly used) lamps

The efficiency of the light source to convert the electric energy into visible light, that is, the light source consumes the light emitted by each Watt, the higher the value, the higher the efficiency of the light source. Light is an important parameter in terms of economy (energy efficiency). Unit: lumen / watt (lm/w). Incandescent lamp: 8-14lm/W single end fluorescent lamp: 55-80 lm/W self ballasted fluorescent lamp: 50-70 lm/W: 80-140 lm/W high-pressure sodium lamp metal halide lamp: 60-90 lm/W tungsten halogen lamp: 15-20 lm/W