What is the luminous flux of a light bulb? Notes when buying LED lights

When approaching lighting technology, consumers are still quite unfamiliar with the term luminous flux. So what is luminous flux and what does it represent in an LED bulb? Learn about luminous flux with Tnhelearning.edu.vn to be able to choose LEDs effectively.

What is the luminous flux of an LED?

In optics, luminous flux is the amount of light emitted from a light source in all directions within one second. Accordingly, the luminous flux of an LED is the amount of light that the LED emits in any direction within one second. The higher the luminous flux of the LED, the brighter the light.

The luminous flux index per 1 watt or luminous efficiency of LEDs is much higher than that of traditional lamps. Therefore, LED lights are considered to be the best and most economical lamps available today.

What is the unit of measurement of luminous flux?

The unit of measurement of luminous flux in the SI system of units (international system of measurement) is lumen , denoted lm.

We have the following formula for luminous flux : Φv = dQv / dt. Where Qv (unit lm.s) is the total luminous energy of a light source.

Currently, many people choose to buy lights based on lamp power alone. However, a lamp with a higher wattage is not necessarily brighter because the brightness depends on the luminescence efficiency of the lamp.

For example, a 7W LED produces a luminous flux equivalent to a 45W halogen bulb because the luminescence efficiency of the LED is 130 lm/watt while the halogen lamp is only 20 – 30 lm/watt.

The efficiency of some lamps on the market can be mentioned as follows: incandescent lamp about 10 – 20 lm/watt, fluorescent lamp about 40 – 50 lm/watt and the highest LED lamp from 90 – 130 lm/watt. watts.

Choosing to buy LED lights need to pay attention to luminous flux?

The luminous flux indicates the total LED light source you want to purchase. So, depending on the area of use, you will choose how the luminous flux is reasonable, avoiding waste.

When installing LED lights in large spaces that require a lot of light, you should choose lamps with large luminous flux and vice versa.

Depending on the area, the interior, the type of light, the design of the house with a lot of light or the closed house, the ceiling height requires a certain amount of light. You can refer to the average luminous flux table for each indoor area in the table below:

From the parameter table of the required luminous flux for each area, the number of LEDs to be installed can be calculated. For example, a kitchen should have a luminous flux of about 300 – 400 lm (lumen). The luminous flux of the indoor LED light is 95 lm/w so you only need to use 1 5W bulb to be bright enough.

So, depending on the area, interior, type of lamp, house design of the house, we can install lights with a large or smaller lumen than the standard, as long as it suits the lighting needs. and space aesthetics.