December 5, 2021

I, Science

The science magazine of Imperial College

Are solar panels a good investment? How do airbag helmets work? Speedy science gives brief answers to quick-fire questions.

How do cyclists’ air bag helmets work?airbag helmet

A discreet neck collar that inflates into a head-protecting hood is clearly going to be a big hit with image-conscious cyclists. But the best part about these airbag helmets, produced in Sweden, is that they are three times safer than traditional hard helmets. Behind this super smart technology is an algorithm that can distinguish between movements generated in normal cycling versus those experienced during accidents. When the collar registers that an accident is occurring, the gas inflator rapidly fills the airbag with helium gas to inflate it.

Why is my snot black?

We’ve all done it – blown our nose and looked at the tissue. If you live in London you will probably have noticed that your snot is grey or black a lot of the time. This is caused by inhaled dirt and dust particles getting caught in the mucus that lines the inside of your nose. Sadly, this is a constant reminder of how polluted the air is in our urban areas. However, it’s not all bad news. This clear sticky mucus helps to keep our airways clean by catching pollutant particles – it’s better to have black snot than black lungs.  

How long does it take to earn your money back from solar panels?

Installing solar panels on your home is no easy decision. At around £4,000 to £6,000, they aren’t cheap, but claims that they dramatically cut your electricity bills and can even bring in money make them a tempting investment for many. But exactly how long would it take to earn back your money? Under the current government “Feed-in Tariff” where home-owners are paid for the spare electricity generated by their panels, it would take 9-10 years to make back the investment. However, new plans to reduce the “Feed-in Tariff” by 87% in January 2016 will increase this payback time to nearly 30 years.

solar panels on house 

How can you make a light bulb that doesn’t require electricity?

Take an old plastic bottle, fill it with water and a bit of bleach, stick it in your ceiling and hey presto you’ve got yourself a 55-watt solar bulb. This is the simple and affordable technology behind the MIT-initiative ‘A Liter of Light’, which aims to provide low cost lighting to communities that either can’t afford or have no access to electricity. It is much more effective than simply a hole in the ceiling because the water-filled bottle refracts light, sending it around the room. It is powerful enough to light up a home, is environmentally friendly, and is easy to make. These nifty skylights last up to five years because the bleach prevents algae from growing in the water.

Watch a video about the solar bottle bulbs below:

Greta Keenan is studying for an MSc in Science Communication.

Images: Hövding airbag helmet, Joshuavr; Solar panels, D. Dimitrova