Ask Mr Brain . . . all will be explained
What is the origin of the 'hot dog'?
The birthplace of this all-American food is generally given as Frankfurt- am-Main in Germany in the 15th century. It travelled to America via hungry German immigrants in the mid-19th century.
But the history becomes unclear as a few competing stories try to explain how the 'hot dog' emerged and why it ended up in a bun.
The most popular tale has it that Charles Feltman, a Coney Island food vendor first sold 'dachshund sausages' on split rolls around 1871.
Later on a cold spring day in 1900, an ice-cream seller who was losing money decided to switch to selling the sausages instead.
He had the 'dachshunds' put in hot-water tanks and sent them into the stands yelling 'Red hot! Get your dachshund sausages while they're hot!'
Sports cartoonist Tad Dorgan heard this pitch and sketched a talking sausage snuggled in a warm bun. Unable to spell the word dachshund, he scribbled 'hot dog'.
Hot dogs have become a worldwide sensation and a typical American treat.
How can we obtain energy from the sun?
Energy sent out from the sun as beams (sunlight) is capable of producing heat, causing chemical reactions and generates electricity.
The sun is an extremely powerful energy source. Solar (connected with the sun) radiation is by far the largest source of energy received by the Earth. But its intensity at the Earth's surface is actually quite low. This is partly because the Earth's atmosphere and its clouds absorb or scatter as much as 54 per cent of all incoming sunlight.
Solar energy has become increasingly attractive as an energy source because of its never-ending supply and its non-polluting nature, unlike fossil fuels such as coal, oil and natural gas.
Two main types of devices are used to capture solar energy and convert it to thermal energy (heat): flat-plate collectors and concentrating collectors. Because the strength of solar radiation at the earth's surface is so low, both types of collectors must be large in area. Even in sunny parts of the world, a collector must have a surface area of about 40 square metres to gather enough energy to serve a person for one day.
The most widely used flat-plate collectors consist of a blackened metal tube, covered with one or two sheets of glass, that is heated by the sunlight falling on it. The heat is then transferred to air or water that flows past the back of the plate. Flat-plate collectors are commonly used for water heating and house heating.
When higher temperatures are needed, a concentrating collector is used. These devices reflect sunlight from a wide area and concentrate it into a small blackened receiver, producing high temperatures.