Do you Know ?

Radio Frequency (300 Hz to 300 GHz) is divided into high frequency (HF), very high frequency (VHF), ultra high frequency or microwave (UHF). RF leakage occurs from television, PC monitor, mobile phones, microwave ovens, transmitters, electric shavers etc. For human body resonance occurs at 60 MHz for a 2 m tall person. RF can cause heat effect when it passes through. Eyes and testes are more prone to heat effect. So do avoid being in strong RF fields, such as those near power radio/RADAR/TV antennas, microwave ovens etc.

Conductive items like metal wire, fences, grills, scrap etc acts as RF generators, when subjected to strong RF radiation. Contact with such items result in shock and burns.

Radio waves are non ionsisng radiation and it's exposure can cause health hazards. Hazard depends on power and frequency of radio waves. Mobile phones use 900/1800 MHz. When signal is weak, the mobile will work at high power and it can cause health hazards.

Background radiation : The radiation dose due to terrestrial cosmic rays is 200 mrem per year, while Monazite sand beach in Kerala has 2 rem/year. A granite house emits 500 mrem/year. House made of rock leaks Radon (the only radioactive gas). As the room lacks ventillation, it can cause harm to the residents.

Nuclear explosion produces EMP - Electro magnetic pulse - by ionising the air. During a nuclear explosion, X - rays (electrons) are produced, and it ionises the air to form EMP. The ionisation layer thus formed can block HF communication for longer periods. EMP damages electronic instruments (radio communication equipments), so EMP hardening methods are
to be used for vital instruments.

Bhabha Atomic Research Centre (BARC) established in 1957 is the largest scientific establishment in India, located at Trombay, Mumbai. The five nuclear reactors of BARC are Apsara (1 MW swimmming pool type reactor), Cirus (40 MW reactor), Zerlina ( Zero Energy Experimental thermal reactor), R5 (100 MW research reactor).

BARC produce radio isotopes for medical and industrial use, sterilisation of medical samples/instruments. Four subsidiaries of BARC are at Kolkata, Bangalore, Srinagar and Gulmarg.
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Jim Corbett was born on 25 July 1875 in Nainital, Uttarakhand. He wrote The man eaters of Kumaon (1944), 'The temple tiger and more man eaters of Kumaon', 'My India', Jungle lore, The man eaters of Rudraprayag and Tree tops.

First Chief Minister of Uttar Pradesh was a Kumaoni - Govind Ballabh Pant.

Robots are used for pilot less air crafts, deep diving, dealing with nuclear fuel, rescue, fire fighting, surveillance, aerial photography, to detect chemical and biological agents in war, space probe, study of extra terrestrial life, at extreme weather conditions, doing work at 24/7 level etc.

Minimum distance to hear an echo is 17 m. The effect of sound on ear remains for 0.1 second. If the sound is reflected back in less than 0.1 second, no echo is heard.

Horse shoe magnets can retain magnetism for a long time if keeper is used with magnet while storing.

Psychrometer measures humidity and it consists of dry & wet bulb thermometers. Take the difference of reading of the two thermometers and refer the humidity chart to get humidity in percentage.

Kieselguhr (diatomaceous earth) is a type of silica formed in the earth from the skeletons of tiny organisms called diatoms. It is used in making fireproof cement, as a filtering medium, in explosives - Nitro glycerin is absorbed into Kieselguhr base to form Dynamite.

Firework flames are coloured due to chemicals added.

White : Potassium, Sulphur, Arsenic, Magnesium, Sb
Red : Strontium, Lithium
Green : Barium
Yellow : Sodium
Blue : Copper

Fuzzy logic is used in expert systems {e.g. - washing machine} to provide human like performance. The digital circuit consists of truth values carry probabilities such as true, very true etc. An expert system [Software/Hardware] works like a specialist consultant with the help of a knowledge base.

Infra red rays heats the objects on which it is directed without heating the surrounding air, thus wastage of energy is avoided.

Bribe detector : Rhodamine base B extra (colourless powder) becomes red (Rhodamine FB) when it comes in contact with the weak HCl (acid) in perspiration (on palm). The colourless powder will be smeared on the bribe (currency).

Horsepower is devised by James Watt. It is the power needed to raise 550 lb through a height of 1 foot in one second.

1 hp = 4500 kgfm/min (MKS) = 746 W. 1 ft = 0.3056 m, 1 lb = 0.4506 kg. Before the invention of the steam engine, horse driven carriages were common in Britain. Later horses were replaced by Iron horses - steam engine. Hence the name horsepower.

Electro Magnetic Pulse (EMP) has no effect on man but can damage electrical and communication equipments. In a ground nuclear explosion, sand and dust are sucked by the fireball and become radioactive. It will form fall out for a long time.

Gamma rays ionise atmospheric gases, thus disrupting communication. EMP vary from few hundred Hz to several MHz with an electric field intensity of 50 kV/m, which can cause damage semiconductor devices, insulation failure in cables, direct damage to equipment, corruption of data in magnetic storage, Radars of MF and UHF (large aperture antenna), ignite petrol vapour and explosives etc.

Radar and radio are blacked out for short or long periods due to ionisation of the atmosphere. Radar can create a field intensity of 200 V/m.

In Radar, a transmitted signal is received after 2 ms, the target is at a distance of 300 km. Wave guides (metal pipes of specific dimension) are used for high frequencies.

Radio communication

Do you read ? - means I have called you more than once, if you are receiving me, reply.

How do you read me - means 1 : unreadable, 2 : readable now and then, 3 : readable with difficulty, 4 : readable, 5 : perfectly readable.

Negative - means No.

Over - means my transmission is ended. I expect a reply from you.

Out - means my transmission is ended. I do not expect a reply from you.

Roger - means Okay, I have received your message.


UHF : 0.3 to 1 GHz
C band : 3.9 to 8 GHz
K : 8 to 16 GHz
Ku : 12.5 to 18 GHz
L : 1 to 1.5 GHz
S : 1.5 to 39 GHz
X : 8 to 12.5 GHz, used in mobile Radars.

Best 50 books I read

Puzzles

1. Puzzles to puzzle you by Shakuntala Devi, Orient publishers, Delhi (Rs 50).
2. More puzzles by Shakuntala Devi, Orient publishers, Delhi (Rs 50).
3. Figuring - the joy of numbers by Shakuntala Devi, Orient publishers, Delhi (Rs 50).
4. Mensa book of brainteasers by Alan Wareham, Orient publishers, Delhi (Rs 50).

Mountaineering books

5. Meeting the mountains by Harish Kapadia, Indus pub, Delhi (Rs 500).
6. Mountain happiness by Brig. DK Khullar, Interprint, Delhi (Rs 500).
7. Great Climbs by Chris Bonnington, Royal Geographic Society & Alpine club, UK.
8. Himalayas playground of Gods by Capt MS Kohli, Vikas pub, Gaziabad.

Motivational books

9. Public speaking and influencing men in business by Dale Carnegie, Taraporevala & sons, Mumbai (Rs 110).
10. See you at the top by Zigzigler, Magna pub co, Mumbai, (Rs 175).
11. Steps to the top by Zigzigler, Magna pub co, Mumbai, (Rs 175).
12. You can win by Shiv Khera (Rs 250).
13. Happiness the key to success and a full life by Sunil Upadhaya, Lotus Hind books, Delhi.
14. Organisational Behaviour, 9 th Edn by John Newstorm & Kelth Davis.