The AnswerBank Articles

How does a fire alarm work

asks nodrog:A. By fire alarm, you mean a smoke detector which is designed to wake people up at the first sign of a fire so that they can evacuate their home safely. Household smoke detectors are made01:00 Mon 21st Jan 2002

In the past salt was the best means of preserving food, how did this work

A. Covering perishable foods like fish and meat, known as curing, is quite an ancient technique. It works because the salt absorbs a lot of water that food holds and locks up any remaining liquid.01:00 Mon 31st Dec 2001

When computer screens appear on television why do we see scrolling lines rather than what s actually displayed on the monitor

A. The answer to this lies in the difference in which our eyes and video cameras perceive images. Q. How is a TV image created A. When we see an image on a television screen that image is01:00 Mon 31st Dec 2001

Why are the number pads of calculators and telephones the opposite way around

A. There are several theories as to why these two systems that share the same ten digits in three rows with the zero on a row by itself have developed with the opposite configuration to each other.01:00 Mon 31st Dec 2001

How does antifreeze work

A. By altering the normal freezing and boiling point of the water in your car's radiator. It can drop the freezing point to as low as -34 degrees Fahrenheit. Q. So it stops it from over heating01:00 Mon 24th Dec 2001

Normally boiling something softens it, so why do eggs go hard-boiled

A. If you know anything about nutrition and food groups then you'll know that eggs are packed with protein. It's the egg's protein content that causes this apparent reverse of states and makes eggs01:00 Mon 24th Dec 2001

What makes glow in the dark toys and stickers glow

A. All glow-in-the-dark products contain phosphors, a substance that radiates visible light after being energized. Q. What gives phosphors this special property A. It's the excitable nature of01:00 Mon 24th Dec 2001

Why does heavy rainfall after a long dry period leave such a distinctive smell

A. This rather pleasant smell is actually the result of actinomycetes, a bacteria, being stirred up by the rain. Q. Why can't we smell the bacteria all the time A. The bacteria grow in the soil01:00 Mon 17th Dec 2001

How does dry cleaning work

A. Dry cleaning was developed in response to delicate fabrics that can't be washed in a normal domestic machine. Also dry cleaning is used for shifting stains that water doesn't deal with very01:00 Mon 17th Dec 2001

Is there any evolutionary advantage for pregnant women suffering morning sickness

A. Although any pregnant woman suffering from morning sickness might not thank you for telling her, morning sickness, on the whole, is thought to be advantageous. It plays an important role in01:00 Mon 17th Dec 2001

Why do soap bubbles look so white

A. Soap foam is made up of tiny air bubbles encircled by thin films of soap and water. As light enters the foam it's reflected back from these film surfaces. Normally, when light changes from moving01:00 Mon 10th Dec 2001

How do lasers work

A. Lasers basically amplify light created by over excited atoms. Atoms are always excited and moving, but once they have become more excited they want to get rid of their excess energy and return01:00 Mon 10th Dec 2001

As a helicopter doesn t speed down a runway, how does it get off the ground

A. Helicopters and airplanes obviously get off the ground in different ways. An airplane uses speed to obtain lift. As it zooms down the runway, the shape and angle of its wings forces air to flow01:00 Mon 10th Dec 2001

Why is there no degree in Kelvin, as in 10 degrees Celsius

A. Generally speaking degrees are just arbitrary units of measurement. So, the point at which water freezes is designated 0 degrees Celsius and the point at which it boils at 100 degrees Celsius.01:00 Mon 03rd Dec 2001

Why doesn t a music tape machine play a note when it s on pause in the same way that a VCR generates a picture when videotape is on pause Are the machines so very different

A. VCR’s and audio tape players work on a similar principle. In both machines a magnetised tape moves past the playback head that picks up the changes in the tapes magnetic field. A signal is01:00 Mon 03rd Dec 2001

Why do some people jump or jerk before they fall asleep

A. This is a very common sleep phenomenon. As you’re peacefully drifting off to sleep you suddenly find yourself violently jumping, pulling you temporarily back into a more conscious state. The01:00 Mon 03rd Dec 2001

Why does biting foil hurt my teeth

A. Biting foil only hurts those of us who have spent more time eating sweets than looking after their teeth and so have fillings. The foil is actually reacting with the metal in your filling. The01:00 Mon 26th Nov 2001

How do safety matches differ from normal matches

A. There are two types of matches: safety matches that need a special striking strip to ignite and matches that you can light by striking almost anywhere. The difference between the two is down to01:00 Mon 26th Nov 2001

Why do bruises change colour

A. Bruises change colour over time, because of the degradation of haemoglobin, the red oxygen carrying pigment red blood corpuscles, in the blood. Q. So it is possible to tell how old a bruise is01:00 Mon 26th Nov 2001

What is the wind chill factor

A. The wind chill factor is the term given to the measure of how much heat the body loses as wind passes over it. Specifically it represents the difference between how much heat loss someone01:00 Mon 19th Nov 2001