copyright@VIJAYKIRAN
2011-2012
This Section contains various Scientific Questions and its Answers collected from various sources news papers,books,magazines and media.Care has been taken to present them as accurately and objectively as possible. However, the developers,designers, or the copy right holders of the site do not give any guarantee in this regard and disclaim any responsibility for any eventual loss or damage whatsoever, direct or indirect, physical or otherwise occurred to the users of such data or details.
What is Nucelar Winter?
Nuclear explosions trigger a horrendous chain reaction. The instantaneous outcome is the thermal and blast effect annihilating everything in and around the area. The mushrooming cloud due to the explosion rises high into the stratosphere, spreading out vast quantities of soot and radioactive debris. Some of the debris fall back to the ground as rain out. The soot and other particles suspended in the atmosphere would block sunlight and lower the global temperatures steeply to subzero levels, ushering in wintery conditions over the planet. This sequence of events has been termed as "Nuclear Winter". As a consequence, photosynthesis would stop leading to the destruction of all green plants.
Subsequently oxygen regeneration would cease and carbondioxide would accumulate. Earth's radiation balance and heat budget would get altered leading to drastic changes in the global circulation pattern. the seasonal monsoons and tropiacl rains may disappear. the duration and extent of the nuclear winter scenario would depend on the location, season and intensity of the explosion. Courtesy : The Hindu
What is the difference between dial up and broadband Internet connections?
The fundamental difference between dialup and broadband connections is the manner in which the connection is made from PC to the Internet.
A dialup service connects to the Internet through a phone line with a maximum speed of 56kbps.
Broadband refers to a connection that has capacity to transmit large amount of data at high speed. Presently a connection having download speeds of 256kbps or more is classified as broadband.
Broadband comes in a number of forms - depending how the data is delivered - for example via cable, satellite and most commonly using a telephone line where as a dialup service always connects to the Internet through a phone line.
While using a dialup connection, we need to pay for a local call every time we dial the Internet. In addition phone line is engaged while we are on the Internet. With a broadband connection, phone line (if existing phone line is used) can still be used while using the Internet and both the phone and the Internet work simultaneously and no dialup costs are incurred. Telecommunication systems were originally built to carry analogue signals. In a dial up connection, modems are used to translate digital into analogue signals and communicating with Internet.
However, analogue transmission between the subcriber and the telephone company is a bandwidth bottleneck. Dialup connection speeds make it more difficult to view certain types of media, such as video, and it can take much longer to download and open emial attachments, play online games and so on.
In an broadband system, digital data does not have to be converted into analogue. it uses a different part of the line's frequency spectrum, offers much wider bandwidth 9more lanes) and does not interfere with the use of the line for voice transmission. When connected to the Internet, such a connection allows surfing or downloading much faster than a dial-up connection. Dialup connection users a built-in modem to connect and does not require a special router, whereas broadband requires a special router or modem.
In terms of security for attack, dialup is more secured then broadband, Broadband users need to use a firewall to keep the computer "invisible" to the outside. Courtesy : The Hindu
Both Infrared and Microwave bands are invisible to the human eye. Then how are IR and microwave images from remote sensing satellites printed? How do they substitute the wavelenghts?
Both infrared and microwaves are part of the electromagnetic spectrum, which stretches from radio waves to gamma rays. each band of this spectrum corresponds to a small range of frequencies. each frequency is uniquely connected with an energy level.
The total spectrum is very wide. Our eyes respond only to a very small band called the visible band. However, different chemicals do react to certain higher or lower level of energy bands and hence can be used as photographic plates for detecting and measuring some of these radiations.
Satellites nowadays use sensors whose working principle is based on photoelectric effect, converting radiation reaching the sensor iinto electric charge, which can then be easily measured and processed.
Essentially, the energy detected over a given spectral band, whether it is in the visible, infrared or microwave band, is converted to an array of digits corresponding to the energy range and radioed to ground stations.
After receiving it, those values corresponding to the measured energy range (known as grey levels) are finnaly printed on a computer screen as a picture or as a conventional photograph. Courtesy : The Hindu
Soaps come in different colours. But why is soap's lather always white in colour?
Lather or foam is nothing but a large collection of small soap bubbles. A soap bubble is , in turn, a very thin film of soap solution enclosing some air. Because of the low surface tension of soap solution, the film can stretch and spread and form innumerable bubbles with a very large total surface area.
Due to this, whatever slight tint is present in the thin film of the coloured soap solution gets subdued. Although a soap film is more or less transparent, the lather or foam looks white because the light striking this large collection of bubbles gets scattered. That is the reason why all kinds of lather or foam appear white. Courtesy : The Hindu
What is the difference between tv screen and computer monitor?
ANSWER I: Computer monitors are capable of accepting signals only from the central processing unit of a computer. Therefore they are unable to reproduce a colour image from a composite video signal whose waveform conforms to a broadcast standard (NTSC, PAL, D-MAC, etc.).
Computer monitors are fitted with connectors characteristic of data processing systems (eg. DINorDB9/15 also called MINI SUB D15Connectors) and do not have an audio circuit.
They are controlled by special adaptors (eg. monochrome or graphic adaptors), which are integrated in the central processing unit of the automatic data processing machine. . Their display pitch size starts at 0.41 mm for medium resolution and gets smaller as resolution increases.
Sor to accommodate the presentation of small, yet well-defined images, computer monitors utilise smaller dot (pixel) sizes and greater convergence standards than those applicable to television receivers. In computer monitors, the video frequency (bandwidth), which is the measurement determining how many dots can be transmitted per second to form an image, is generally 15 MHz or greater. But in case of TV or video monitors, the bandwidth is generally not more than 6 MHz.
The horizontal scanning frequency of these monitors varies according to the standards for various display modes, generally from 15 kHz to over 155 kHz. Some are capable of multiple horizontal scanning frequencies. Horizontal scanning frequency of video/TV monitors is fixed, usually 15.6 or 15.7 kHz depending on applicable television standard.
ANSWER II: In all computer monitors, the image is painted on the screen by an electron beam that scans from one side of the display to the other. In television, transitions in colour, intensity, and pattern as the beam scans across the screen tend to be gradual.
But, the transitions a computer monitor typically processes are abrupt as areas of high intensity transform to areas of black as text is placed on the screen. Television uses a process that relies on the brain's ability to integrate gradual transitions in pattern that the eye sees as the image is painted on the screen. During the first phase of screen drawing, even-numbered lines are drawn. In the next, odd lines are drawn. The eye integrates the two images to create a single image. The scan is interlaced. But, a computer viewer has different needs. The viewer is sitting within a foot or two of the screen and viewing a frequently changing text image.
If a computer monitor used the same method of display as TV, many transitions would produce an annoying amount of flicker, because the brain is less able to integrate the dramatic transition from bright to dark.
Also, a secondary problem occurs due to inability of the monitor to paint interlaced images exactly in between the lines from preceding scan.
Text images makes this much more visible to the eye at the close range, and at the relatively slower speeds of an interlaced scan. So, computer monitors use a technique that paints one continuous image at a time and is said to be non-interlaced.
Consequently, although the scan frequencies of the TV receiver and monitor are similar, computer monitors must be designed to paint every line during every write of the picture to prevent flicker. This requires electronics that operate twice the speed as that of a television. Courtesy : The Hindu
The Touch Sensor has a textured coating across the glass face. This coating is sensitive to pressure and registers the location of the user's finger when it touches the screen. The controller is a small PC card that connects the touch sensor to the PC. It takes information from the touch sensor and translates it into information that PC can understand. The Software Driver is a software update for the PC system that allows the touchscreen and computer to work together. It tells the computer's operating system how to interpret the touch event information that is sent from the controller.
There are three basic systems that are used to recognise a person's touch — Resistive, Capacitive and Surface acoustic wave.
The resistive system consists of a normal glass panel that is covered with a conductive and a resistive metallic layer. These layers are held apart by spacers, and a scratch-resistant layer is placed on top of the whole set up. An electrical current runs through the two layers while the monitor is operational. When a user touches the screen, the two layers make contact in that spot. The change in electrical field is noted and coordinates of the point of contact are calculated. Once the coordinates are known, a special driver translates the touch into something that the operating system can understand, much as a computer mouse driver translates a mouse's movements into a click or drag.
In the capacitive system, a layer that stores electrical charge is placed on the glass panel of the monitor. When a user touches the monitor with his or her finger, some of the charge is transferred to the user, so the charge on the capacitive layer decreases. This decrease is measured in circuits located at each corner of the monitor. The computer calculates, from the relative differences in charge at each corner, exactly where the touch event took place and then relays that information to the touch screen driver software. One advantage of the capacitive system is that it transmits almost 90 per cent of the light from the monitor, whereas the resistive system only transmits about 75 per cent. This gives the capacitive system a much clearer picture than the resistive system.
The surface acoustic wave system uses two transducers (one receiving and one sending) placed along the x and y axes of the monitor's glass plate. Also placed on the glass are reflectors — they reflect an electrical signal sent from one transducer to the other. The receiving transducer is able to tell if the wave has been disturbed by a touch event at any instant, and can locate it accordingly. The wave setup has no metallic layers on the screen, allowing for 100-percent light throughput and perfect image clarity. This makes the surface acoustic wave system best for displaying detailed graphics (both other systems have significant degradation in clarity).
Another area in which the systems differ is which stimuli will register as a touch event. A resistive system registers a touch as long as the two layers make contact, which means that it doesn't matter if you touch it with your finger or a rubber ball. A capacitive system, on the other hand, must have a conductive input, usually your finger, in order to register a touch. The surface acoustic wave system works much like the resistive system, allowing a touch with almost any object — except hard and small objects like a pen tip. (Source: www.howstuffworks.com and www.touchscreens.com ) Courtesy : The Hindu
Frequent switching on/off the fluorescent lamp occurs through several cycles of filament heating and cooling. If the cycles of heating and cooling of the filament are too frequent this may result in tremendous loss of oxide coating (at the rate of 10-20 micro-grams/cm{+2} per cycle).
The loss of oxide coating in the cathode filament through rapid on/off (heating/cooling) operations will lead to poor performance of the filament in generating thermions to initiate the discharge process. This in turn will reduce the life of the fluorescent lamp. Life of a conventional fluorescent lamp usually rated for several thousand hours of continuous burning can be halved or made still less, just by frequent switching on/off. Courtesy : The Hindu
What is Nucelar Winter?
Nuclear explosions trigger a horrendous chain reaction. The instantaneous outcome is the thermal and blast effect annihilating everything in and around the area. The mushrooming cloud due to the explosion rises high into the stratosphere, spreading out vast quantities of soot and radioactive debris. Some of the debris fall back to the ground as rain out. The soot and other particles suspended in the atmosphere would block sunlight and lower the global temperatures steeply to subzero levels, ushering in wintery conditions over the planet. This sequence of events has been termed as "Nuclear Winter". As a consequence, photosynthesis would stop leading to the destruction of all green plants.
Subsequently oxygen regeneration would cease and carbondioxide would accumulate. Earth's radiation balance and heat budget would get altered leading to drastic changes in the global circulation pattern. the seasonal monsoons and tropiacl rains may disappear. the duration and extent of the nuclear winter scenario would depend on the location, season and intensity of the explosion. Courtesy : The Hindu
What is the difference between dial up and broadband Internet connections?
The fundamental difference between dialup and broadband connections is the manner in which the connection is made from PC to the Internet.
A dialup service connects to the Internet through a phone line with a maximum speed of 56kbps.
Broadband refers to a connection that has capacity to transmit large amount of data at high speed. Presently a connection having download speeds of 256kbps or more is classified as broadband.
Broadband comes in a number of forms - depending how the data is delivered - for example via cable, satellite and most commonly using a telephone line where as a dialup service always connects to the Internet through a phone line.
While using a dialup connection, we need to pay for a local call every time we dial the Internet. In addition phone line is engaged while we are on the Internet. With a broadband connection, phone line (if existing phone line is used) can still be used while using the Internet and both the phone and the Internet work simultaneously and no dialup costs are incurred. Telecommunication systems were originally built to carry analogue signals. In a dial up connection, modems are used to translate digital into analogue signals and communicating with Internet.
However, analogue transmission between the subcriber and the telephone company is a bandwidth bottleneck. Dialup connection speeds make it more difficult to view certain types of media, such as video, and it can take much longer to download and open emial attachments, play online games and so on.
In an broadband system, digital data does not have to be converted into analogue. it uses a different part of the line's frequency spectrum, offers much wider bandwidth 9more lanes) and does not interfere with the use of the line for voice transmission. When connected to the Internet, such a connection allows surfing or downloading much faster than a dial-up connection. Dialup connection users a built-in modem to connect and does not require a special router, whereas broadband requires a special router or modem.
In terms of security for attack, dialup is more secured then broadband, Broadband users need to use a firewall to keep the computer "invisible" to the outside. Courtesy : The Hindu
Both Infrared and Microwave bands are invisible to the human eye. Then how are IR and microwave images from remote sensing satellites printed? How do they substitute the wavelenghts?
Both infrared and microwaves are part of the electromagnetic spectrum, which stretches from radio waves to gamma rays. each band of this spectrum corresponds to a small range of frequencies. each frequency is uniquely connected with an energy level.
The total spectrum is very wide. Our eyes respond only to a very small band called the visible band. However, different chemicals do react to certain higher or lower level of energy bands and hence can be used as photographic plates for detecting and measuring some of these radiations.
Satellites nowadays use sensors whose working principle is based on photoelectric effect, converting radiation reaching the sensor iinto electric charge, which can then be easily measured and processed.
Essentially, the energy detected over a given spectral band, whether it is in the visible, infrared or microwave band, is converted to an array of digits corresponding to the energy range and radioed to ground stations.
After receiving it, those values corresponding to the measured energy range (known as grey levels) are finnaly printed on a computer screen as a picture or as a conventional photograph. Courtesy : The Hindu
Soaps come in different colours. But why is soap's lather always white in colour?
Lather or foam is nothing but a large collection of small soap bubbles. A soap bubble is , in turn, a very thin film of soap solution enclosing some air. Because of the low surface tension of soap solution, the film can stretch and spread and form innumerable bubbles with a very large total surface area.
Due to this, whatever slight tint is present in the thin film of the coloured soap solution gets subdued. Although a soap film is more or less transparent, the lather or foam looks white because the light striking this large collection of bubbles gets scattered. That is the reason why all kinds of lather or foam appear white. Courtesy : The Hindu
What is the difference between tv screen and computer monitor?
ANSWER I: Computer monitors are capable of accepting signals only from the central processing unit of a computer. Therefore they are unable to reproduce a colour image from a composite video signal whose waveform conforms to a broadcast standard (NTSC, PAL, D-MAC, etc.).
Computer monitors are fitted with connectors characteristic of data processing systems (eg. DINorDB9/15 also called MINI SUB D15Connectors) and do not have an audio circuit.
They are controlled by special adaptors (eg. monochrome or graphic adaptors), which are integrated in the central processing unit of the automatic data processing machine. . Their display pitch size starts at 0.41 mm for medium resolution and gets smaller as resolution increases.
Sor to accommodate the presentation of small, yet well-defined images, computer monitors utilise smaller dot (pixel) sizes and greater convergence standards than those applicable to television receivers. In computer monitors, the video frequency (bandwidth), which is the measurement determining how many dots can be transmitted per second to form an image, is generally 15 MHz or greater. But in case of TV or video monitors, the bandwidth is generally not more than 6 MHz.
The horizontal scanning frequency of these monitors varies according to the standards for various display modes, generally from 15 kHz to over 155 kHz. Some are capable of multiple horizontal scanning frequencies. Horizontal scanning frequency of video/TV monitors is fixed, usually 15.6 or 15.7 kHz depending on applicable television standard.
ANSWER II: In all computer monitors, the image is painted on the screen by an electron beam that scans from one side of the display to the other. In television, transitions in colour, intensity, and pattern as the beam scans across the screen tend to be gradual.
But, the transitions a computer monitor typically processes are abrupt as areas of high intensity transform to areas of black as text is placed on the screen. Television uses a process that relies on the brain's ability to integrate gradual transitions in pattern that the eye sees as the image is painted on the screen. During the first phase of screen drawing, even-numbered lines are drawn. In the next, odd lines are drawn. The eye integrates the two images to create a single image. The scan is interlaced. But, a computer viewer has different needs. The viewer is sitting within a foot or two of the screen and viewing a frequently changing text image.
If a computer monitor used the same method of display as TV, many transitions would produce an annoying amount of flicker, because the brain is less able to integrate the dramatic transition from bright to dark.
Also, a secondary problem occurs due to inability of the monitor to paint interlaced images exactly in between the lines from preceding scan.
Text images makes this much more visible to the eye at the close range, and at the relatively slower speeds of an interlaced scan. So, computer monitors use a technique that paints one continuous image at a time and is said to be non-interlaced.
Consequently, although the scan frequencies of the TV receiver and monitor are similar, computer monitors must be designed to paint every line during every write of the picture to prevent flicker. This requires electronics that operate twice the speed as that of a television. Courtesy : The Hindu
How do touch screens work?
The Touch Sensor has a textured coating across the glass face. This coating is sensitive to pressure and registers the location of the user's finger when it touches the screen. The controller is a small PC card that connects the touch sensor to the PC. It takes information from the touch sensor and translates it into information that PC can understand. The Software Driver is a software update for the PC system that allows the touchscreen and computer to work together. It tells the computer's operating system how to interpret the touch event information that is sent from the controller.
There are three basic systems that are used to recognise a person's touch — Resistive, Capacitive and Surface acoustic wave.
The resistive system consists of a normal glass panel that is covered with a conductive and a resistive metallic layer. These layers are held apart by spacers, and a scratch-resistant layer is placed on top of the whole set up. An electrical current runs through the two layers while the monitor is operational. When a user touches the screen, the two layers make contact in that spot. The change in electrical field is noted and coordinates of the point of contact are calculated. Once the coordinates are known, a special driver translates the touch into something that the operating system can understand, much as a computer mouse driver translates a mouse's movements into a click or drag.
In the capacitive system, a layer that stores electrical charge is placed on the glass panel of the monitor. When a user touches the monitor with his or her finger, some of the charge is transferred to the user, so the charge on the capacitive layer decreases. This decrease is measured in circuits located at each corner of the monitor. The computer calculates, from the relative differences in charge at each corner, exactly where the touch event took place and then relays that information to the touch screen driver software. One advantage of the capacitive system is that it transmits almost 90 per cent of the light from the monitor, whereas the resistive system only transmits about 75 per cent. This gives the capacitive system a much clearer picture than the resistive system.
The surface acoustic wave system uses two transducers (one receiving and one sending) placed along the x and y axes of the monitor's glass plate. Also placed on the glass are reflectors — they reflect an electrical signal sent from one transducer to the other. The receiving transducer is able to tell if the wave has been disturbed by a touch event at any instant, and can locate it accordingly. The wave setup has no metallic layers on the screen, allowing for 100-percent light throughput and perfect image clarity. This makes the surface acoustic wave system best for displaying detailed graphics (both other systems have significant degradation in clarity).
Another area in which the systems differ is which stimuli will register as a touch event. A resistive system registers a touch as long as the two layers make contact, which means that it doesn't matter if you touch it with your finger or a rubber ball. A capacitive system, on the other hand, must have a conductive input, usually your finger, in order to register a touch. The surface acoustic wave system works much like the resistive system, allowing a touch with almost any object — except hard and small objects like a pen tip. (Source: www.howstuffworks.com and www.touchscreens.com ) Courtesy : The Hindu
Does frequent switching on/off of a fluorescent lamp reduce its life?
Frequent switching on/off the fluorescent lamp occurs through several cycles of filament heating and cooling. If the cycles of heating and cooling of the filament are too frequent this may result in tremendous loss of oxide coating (at the rate of 10-20 micro-grams/cm{+2} per cycle).
The loss of oxide coating in the cathode filament through rapid on/off (heating/cooling) operations will lead to poor performance of the filament in generating thermions to initiate the discharge process. This in turn will reduce the life of the fluorescent lamp. Life of a conventional fluorescent lamp usually rated for several thousand hours of continuous burning can be halved or made still less, just by frequent switching on/off. Courtesy : The Hindu
1. An inch of time is an inch of gold, but you can’t buy that inch of time with an inch of gold. -Chinese Proverb 2. You can’t catch a cub without going into the tiger’s den. -Chinese Proverb 3. A book holds a house of gold. -Chinese Proverb 4. A fall in a ditch makes you wiser. -Chinese Proverb 5. A tiger never returns to his prey he did not finish off. -Chinese Proverb 6. Tension is what you think you should be. Relaxation is who you are. -Chinese Proverb 7. The great question is not whether you have failed, but whether you are content with failure. -Chinese Proverb 8. The senses are like a reversible coat. They can go outside to the world, or inside to the sould. -Buddhist Proverb 9. He who has health has hope; and he who has hope has everything. -Arabic Proverb 10. In the moment of crisis, the wise build bridges and foolish build dams. -Nigerian Proverb 11. To know the road ahead, ask those coming back. -Chinese Proverb 12. Everything in the past died yesterday, everything in the future was born today. -Chinese Proverb 13. When there is no enemy within, the enemies outside cannot hurt you. -Chinese Proverb 14. Do not try to fight a lion if you are not one yourself. -African Proverb 15. The mouth which eats does not talk. -African Proverb 16. You must judge a man by the work of his hands. -African Proverb 17. A man who pays respect to the great paves the way for his own greatness. -African Proverb 18. A barber does not shave himself. -African Proverb 19. If a child washes his hands, he could eat with kings. -African Proverb 20. A talkative bird will not make a nest. -African Proverb 21. Before shooting, one must aim. -African Proverb 22. A house divided cannot stand. -Arabic Proverb 23. Leave evil, it will leave you. -Arabic Proverb 24. A book is like a garden carried in the pocket. -Arabic Proverb 25. Envy is a weight not placed by its bearer. -Arabic Proverb 26. Silence is the sign of approval. -Arabic Proverb 27. Show him death and he will be content with fever. -Arabic Proverb 28. Blood can never turn into water. -Arabic Proverb 29. The tongue of the ignorant is the key to his death. -Arabic Proverb 30. One hand cannot clap. -Arabic Proverb 31. Plant each day and you will eat. -Arabic Proverb |
