Light Emitting Diode

Light Emitting Diode

Subject: Science

Section: Msc

Context- Using LED bulbs in trains can help the Indian Railway achieve its Net Zero target by 2030.

Concept-

• Lighting accounts for nearly 5% of global CO2 emissions.
• A global switch to energy efficient light emitting diode (LED) technology could save over 1,400 million tons of CO2 and avoid the construction of 1,250 power stations.
• With savings of up to 50-70%, LED lighting has been recognized as one of the most actionable and ready-to-implement technologies for cities to transition to a low carbon economy and peak emissions in the next decade.

Fluorescent Bulbs vs LED Bulb:

• Fluorescent bulbs emit omnidirectional light while that of LEDs is directional.
  • Fluorescent bulbs radiate light 360 degrees around the tube’s circumference.
  • Only a small percentage of this light is directed to the area directly below (such as at a desk in an office). The rest radiates in less useful directions unless the bulbs are installed inside reflectors, which still scatter some of the light.
  • On the other hand, LED lights are directional in that most of their light radiates in a 110 degree They don’t require the bulky reflectors of fluorescent tubes.
• LED lighting is more energy-efficient than fluorescent bulbs.
  • According to the U.S. Department of Energy, a 12 watt LED light puts out the same lighting as a 15 watt fluorescent light. In other words, LEDs use 20% less power.
• Fluorescent bulbs emit UV light.
  • Fluorescent bulbs emit some UV light, which is hard on the eyes and causes color fading in fabrics. This is wasted energy.
  • LED lighting does not emit UV light. In fact, its light emission lies entirely in the visible light range.
  • The phosphors within LED Lamps convert UV to white light.
• LED lights last longer than fluorescent bulbs.
  • LED lights last up to 13 times longer than fluorescent bulbs. This means a big savings in maintenance costs.
• LED lights are more rugged than fluorescent lights.
  • LEDs are solid state lights, which are more damage resistant than the fragile tubes of fluorescent lights. Fluorescent bulbs contain inert gas within the glass casing. Breaking fluorescent bulbs also exposes one to mercury.
• LEDs do not flicker near the end of their life.
  • Fluorescent lights go through a period of flickering before burning out. However, the usefulness of the light ends when the flickering starts.
• Fluorescent bulbs contain mercury, and may therefore present waste disposal issues.