How to Calculate Lumens Per Watt
how to calculate lumens per watt The number of lumens per watt is a characteristic of each light bulb and is a measure of the bulb's efficiency. It depends on a number of factors, including how the bulb makes light, the quality of the materials from which the bulb is made and how much of the input energy is wasted as heat. The packaging tells you the number of watts of power each bulb consumes and the number of lumens of light it puts out. The number of lumens per watt is simply the ratio of these two numbers. What Is a Lumen? A lumen is defined in the SI (metric) measurement system as the amount of luminous flux emitted per second in a unit solid angle of one steradian by a source of one candela. A steradian is simply an area at a distance r from the source equal to a circle with area r2. What Is a Watt? A watt is a unit of power in the SI system. In that system, work and energy are measured in joules, and because power is the rate of doing work, one watt is equal to one joule per second. The power in an electrical circuit, which is equal to the voltage across the circuit multiplied by the current, is also measured in watts. The wattage of a light bulb is the amount of energy the bulb consumes, and it's what you end up paying for when your [...]