There was recently a reply to a query regarding fluorescent lights, their dangers and energy efficiencies. Please can you also explain the halogen light bulb, how it works and the energy rating? - B.M. (Kilkenny)
A normal halogen light bulb is made up of a small quartz envelope.
Because of being smaller than a normal bulb, the envelope is made of quartz rather than glass, which would melt under the intense heat. At the centre of the lamp is a tungsten filament. The envelope also contains a gas from the halogen group, which combines with tungsten vapour. If the temperature is high enough, the gas will combine with tungsten atoms as they evaporate, and redeposit them on the filament.
This recycling process allows the filament to last a lot longer than a usual light bulb.
It is also possible to run the filament hotter, allowing more light per unit of energy.
It will still generate a lot of heat, and since the filament is so close to the outside, remains its only safety hazard.
Studies by greenhouse management consultancy Energetics have found the lights use about 730 kilowatt hours a year.
This is about twice as much as a modern fridge that boasts a four-star energy rating.
Visa application for Canada
I recently read the answer to the problem of applying for an overseas visa, and it has cleared up any issues I had with travelling to Australia. However, does the same website allow you to apply for a visa to stay in another country, say, in this case, Canada? - H.L. (Eastwood)
The Australian Department of Immigration and Citizenship is responsible for managing travel to Australia, but not from Australia to other countries.
The Canadian counterpart to the Department is Citizenship and Immigration Canada.
Its website http://www.cic.gc.ca/english/index.asp allows you to apply for a visa to travel to or stay in Canada. The Australian website has contact details of overseas departmental offices and should be referred to when preparing to travel overseas.
Most countries will have an equivalent body to the Department of Immigration and Citizenship.
Refer to this when applying for a visa in that country.
Where to write
Questions should be addressed to What's Your Problem? The Advertiser, GPO Box 339, Adelaide, 5001, or email email@example.com.
Please include name and address, not necessarily for publication.Need more information? Contact the State Library of SA inquiry service on 82077250/7252 or country (freecall) 1800182013.
WWW home page: http://www.slsa.sa.gov.au/goto/askus
Please note that answers published are not necessarily supplied by the State Library.