The SI unit of luminous intensity is the candela (abbreviated cd), which is a primary unit. The derived SI unit of luminous flux is the lumen (abbreviated lm). These are based on the sensitivity of the human eye to light. Light sources are often evaluated based on their luminous efficacy, which is defined as the luminous flux divided by the power consumed and is measured in In a physical or online store, find manufacturer’s specifications for representative incandescent, halogen, high-temperature-discharge, LED, and fluorescent lamps of similar luminous flux and compare their luminous efficacy.

Question

What will be an ideal response?

Answer 1

I chose all lamps that could be screwed into a regular medium-base socket



In this light-output range, the high pressure sodium lamp, compact fluorescent, and LED are comparable. All three high-efficiency options are about a factor of 4 better than incandescent or halogen bulbs. Eventually, LED’s have the potential to be much more efficient than fluorescents, but what is on the market now is not there yet. They are improving rapidly – this is the first year in which the LED lamp has been the most efficient when I did this exercise. Previously, the high-pressure sodium lamp was most efficient.