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Using Light Dependent Resistors: Powering The Automatic Street Lights?Find Out!

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Hello world

blind man

Have you ever heard of LDRs or light dependent resistors, and how they can be used in our street lights?

Well, Light Dependent Resistors (LDRs) are highly resistant resistors that use incident light energy that is otherwise getting wasted to power devices. When the incident light energy falls on the highly resistant surface of the resistor, the photons in the light energy free the electrons and put them in an excited state. The excited electrons then jump into the conduction band. So that?s how the resistant surface loses its resistance during the day. At night, the resistance of the surface is extremely low, so the electrons move back towards the low resistant surface and that switches on the light bulb. During the day, when the electrons move away from the surface, it switches off the light bulb. This basic model is able to switch ON/OFF the light bulbs and it works on light energy.

So why do we need this?

Well, on an average, a city spends 10-40% of its electric bill on power consumption for street lights and that is one of the most important things that a city requires and cannot do without. So, if we can implement this in our city, it would save a lot of money. Not just because it is an eco-friendly option that utilises lesser fossil fuels, but also because it is easy to maintain, costs less to set up and will save a ton of money when it comes to electricity. Most cities in Europe, have adopted this system to power their street lights. As they are easy to build and maintain, it can be implemented in most cities as well. If we utilize this model for our city it can save costs and help the environment.

Street Lamps in India

Street lamps are an important part of every city as they are not helpful for drivers but mostly for pedestrians. The government of India, as of 2014, has installed a capacity of generating 255681.46 MW, according to the CEA, Ministry of Power. Out of this, Coal based units generate 154170.89 MW, gas based units generate 22971.25 MW, diesel gives an input of 1199.75 MW, nuclear gives 4780 MW, hydro contributes to 40867.43 MW and renewable energy gives 31692.14 MW. These numbers are staggering and can be reduced drastically with a smarter system in place.

LDR not only saves energy but also reduces cost. In a time such as ours, we need every possible method to reduce consumption of fossil fuels and look for better solutions.


State Key Laboratory of Millimeter Waves, Department of Radio Engineering Southeast University, Nanjing 210096, China

ECE Department, Pusa Institute of Technology, New Delhi, India

EEE Department, HMR Institute of Technology & Management, New Delhi, India

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