Luminous efficacy

Luminous efficacy measures how effective a light source is at producing visible light. Think of it like a magic wand that turns electricity into light that we can see. Some wands are better than others at producing light, so they can make more light with the same amount of electricity.

So, a light bulb with high luminous efficacy is like a really good wand that can create a lot of light with only a little bit of magic (electricity). But a bulb with low luminous efficacy is like a wand that's not very good at making light - it needs a lot of magic just to create a little bit of light.

Scientists use a special unit called lumens to measure how much visible light a bulb produces. So, if a bulb has high luminous efficacy, it will produce more lumens for the same amount of electricity compared to a bulb with low luminous efficacy.

When we're picking out light bulbs or designing lighting systems, we want to choose light sources with high luminous efficacy. That way, we can save electricity and still get the amount of light we need. Plus, it's better for the environment when we use less electricity.