Question Corner

QUESTION: How are diet eggs produced?

J.John Silas, Chennai

ANSWER: Another name for diet eggs is "designer eggs". The name was coined after extensive research conducted at the University of Alberta, Canada for 12 years. Apparently, it is in the feeding process where the secret of diet eggs lies.

The feed is being manufactured by the company itself. Normally, Omega-3 poly unsaturated fatty acids (PUFA) and vitamin E protein are incorporated into natural grains and then fed to the chicks.

The hens lay eggs which are low in cholestrol and resistant to pathogenic bacteria as Salmonella. Currently in India there are two such diet egg producers. One is at Mysore and the other is at Bannerghatta in Bangalore.

M.Vignesh, Madurai

QUESTION: Why does the surface of the incandescent light bulbs become progressively greyer over time?

ANSWER 1 The greying of the inner surfaces of incandescent bulbs is the result of gradual evaporation of tungsten from the filament while the light is on. This evaporation eventually makes the filament so thin it burns out.

Various methods have been developed to reduce greying. Filaments of the first incandescent lamps burnt in a vacuum, but it was soon found that introducing inert gas to the bulb reduced the rate of greying.

A mixture of nitrogen and argon is used today. In addition, ``getters'' reactive metal such as tantalum and titanium can be placed near the filament to attract the tungsten so that it is not deposited on the glass.

Alternatively, a small amount of abrasive tungsten powder can be placed in the bulb. Shaking it occasionally will remove the grey coating from the surface of the glass.

Greying can almost eliminated by introducing a small amount of the halogens iodine and bromine. As tungsten evaporates from the filament, it reacts with the halogens which then redeposit the tungsten on the filament. This keeps the bulb wall clean.

To prevent the tungsten halides from condensing on the bulb and breaking the cycle, the temperature of the bulb wall must be at least 500 -C. This is too hot for glass bulbs, which normally operate at about 150 -C, so fused quartz (silicon dioxide) must be used instead.

Compared with ordinary incandescent lamps, quartz-halogen lamps have longer lives and maintain their light output over time. For example, a quartz-halogen lamp with a 2000-hour life will have dimmed by less than 5 per cent by the time it burns out. When an incandescent lamp with a 1000- hour life burns out, it will have dimmed by more than 15 per cent.

ANSWER 2: This can be explained by the fact lights work not by emitting light but by sucking dar. ``Dark sucker'' theory is too complex to be described here in detail, but it proves the existence of dark, that dark is heavier than light, that dark is coloured, and that it travels faster than light.

To answer your question, a bulb becomes darker over time because of all the dark has sucked in. Similarly, a candle, which is a primitive type of dark sucker, has a white wick when new and this becomes black when used, due to all the dark which has been sucked into it.- New Scientist

Is there any easy method to check the purity of honey ?

J.John Silas, Chennai

Why do some people feel sleepy while reading?

T.R.Anandan, Coimbatore, T.N.

Why does smoke move upwards, which is opposite direction to the gravity ?

M.Arulappa, Vilupuram, T.N.

How do cold blooded animals tolerate very narrow range of temperatures in life ?

V.V.Balasubramanyam, Anantapur, A.P.

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