Category Science & Technology

Where is the world’s oldest underground railway?

               The world’s first underground railway was built in London city. Once the route was planned, a great trench was cut along the streets. Then the railway tracks were laid and the trench was covered over again, to restore the road and create a railway tunnel underneath. This method of tunnel making is called ‘cut and cover’.

               The original route of the London underground railway was nearly four miles long from Paddington Station to Farringdon Street in London. It was opened on 10th January 1863. The first trains were hauled by steam engines and the smoke in the tunnels caused discomfort. But this being the world’s first under-ground railway, it was a cause of great excitement. Today, the most extensive underground railway system in the world is in London.

               In 1890, a deep tunnel railway was also built in London through which electric trains could run. The earlier trains did not have any windows as they were thought to be unnecessary if the train was only to travel through a tunnel. The deepest underground point on the railway line is 67.3 m deep near Hampstead. The longest single journey is from Epping to West Ruislip which is 54.9 km long.

               Many other countries of the world also have underground railways. In Paris an underground railway was opened in 1900. In the United States of America the first practical subway line was constructed in Boston between 1895 and 1897. New York City opened the first underground railway in 1904, now the largest system in the world. The world’s busiest ever metro system has been the Greater Moscow in Russia (Opened in 1935).

               In Canada, Toronto opened a subway in 1954. In Japan, the Tokyo subway was opened in 1927. India’s first underground railway was inaugurated in Calcutta in 1985. This has relieved pressure on Calcutta’s traffic problems to a considerable extent.

               Construction of underground railways is a very complicated process. Normally deep trenches are dug by the side of main roads to lay rails. The walls of these trenches are made of bricks and are covered with strong steel beams to make the roofs. The trains run underground and other vehicles above them on the roads. 

What is Artificial Intelligence?

               When we speak of intelligence we refer to the natural intelligence of people which means their inherent mental ability. But artificial intelligence is the intelligence of machines that can think like human minds. Of late, scientists have developed computers which can perform tasks that require intelligence. The successful performance of such tasks which need some thinking and analysis has again generated the old debate whether machine is superior to man or vice versa?

               Nowadays machines can easily recognize and read printed words. Autopilots, which are computerized machines, can fly aircrafts. These intelligent machines can also recognize and respond to sound and voice and also learn to rectify the mistakes committed. Even computers can play chess so brilliantly that they sometimes outwit the human beings. The whole world was stunned when an IBM computer defeated the world champion Gary Kasparov in a game of chess. But does this mean that artificial intelligence is superior to the natural intelligence of man?

               A computer carries out a series of operations as per the programs developed by computer programmers. This means that the human intelligence works behind the artificial intelligence of machines. Artificial intelligence has its limitations as it depends on the amount of stored information in it to make a decision whereas the natural intelligence is not handicapped by any such limitations.

               Now research is underway to create sound links with computers so as to enable them to recognize human speech and thus receive the feedback orally rather than inserting the instructions through the keyboard. This development of direct interaction with machines or computers would be another milestone in the field of artificial intelligence.

               Now artificial intelligence research covers the areas of planning, language understanding, and pattern recognition and knowledge representation. But whether it can ever surpass the natural intelligence of man, only the future can say.

 

How do trawlers fish?

               There is perhaps no human activity older, more varied or stranger, than fishing. He tricks and catches fish in different ways, such as using his bare hand, or fishing even with harpoon guns in whaling! But the method most used today is the one by which it produces the biggest share of commercial fishing known as trawling. Do you know how do trawlers fish?

               Trawlers fish with a bag-size net. It is let out on long warps or ropes. The fish are swept in at the wide, open end and then get trapped at the narrower, closed end. The trawler may be between 100 to 1500 metres long or more. In this system, the motorized fishing boats trawl by towing a large net in three different ways to keep the mouth of the net open. Firstly, a beam can be placed across the head of the net; secondly a pair of boats can be used – one at each side of the net to tow it and thirdly, some floating weights, called otter boards can be attached to the sides of the mouth of the net.

               However, the beam trawl is only used on a few small fishing crafts, and on the other hand, pair trawling is used to catch fishes from the bottom of the sea to enormous depths, sometimes at the range of 1500 metres or more. When the net is full, powered winches haul it on the board through a ramp. The otter trawl is widely used and is employed on almost every fishing technique except the smaller trawlers.

               The net gathers in everything including eggs, newly hatched fishes and algae. But this system is considered to be very destructive and alarming in the context of overfishing along the seas. Sometimes an entire fleet of fishing vessels is headed by a large factory ship fitted out just for processing of the catch. A single “sweep” of the net often taken in terms of tonnes of fish provides an idea of the quantity of fish caught in rich seas. Deep sea fishes like sardines and herrings together account for eighteen percent of the world’s catch.

               Today, the large motor fishing vessels are fitted with sonar or echo-sound equipments to locate a shoal of fish.

 

Where would a ball fall when thrown inside a running train?

               You might say that the ball would fall behind the person who throws it because he would have moved forward with the moving train. But in fact this is not correct.

               You can perform a simple experiment to answer this question. You would be surprised to find that the ball lands right in your hand when thrown upward inside the moving train. Do you know why it happens so?

               In a moving train everything inside the train also moves with the speed of the train, for example, the fans, passengers, you and the ball in your hand. When you throw up the ball, a part of the speed of the train is imparted to it. It acquires a vertical motion in addition to its horizontal motion. The passengers in the train cannot see its horizontal motion but only its upward and downward movements.

               Imagine a man outside the train, who is watching your experiment. As we have said the ball possesses both vertical and horizontal motions, both these motions combined together make the ball travel along a parabolic path. The observer outside the train will see the ball moving in a parabolic path but a passenger in the train will see only the up and down motions of the ball.

               Now the question arises whether the ball follows the parabolic path or just moves up and down? Out of these two which one is right? In fact, all motion is relative to the observer. There is nothing like absolute motion and hence the motion of the ball is different for the two observers. 

How does an Electric Bell function?

               When you push the button of an electric door bell or calling bell it keeps on ringing as long as the button remains pressed.

               Do you know how does it function? An electric bell is a simple device based on the magnetic effects of electric current. It is used in offices, houses, industries and for fire alarms.

               It consists of a U-shaped electromagnet and a soft-iron armature. The armature has a small hammer for striking the gong. This hammer hits the gong repeatedly and produces sound. The gong is made of a metal. For operating the bell, a push button is pressed. In an electric bell, the button is a switch that connects the supply of electricity to the bell.

               When the button of the bell is pressed, the current flows through electromagnet winding, armature, contact spring and the contact screw. The flow of the current magnetizes the soft-iron core of the electromagnet. This attracts the armature, causing the attached hammer to strike the metal gong and thereby produce sound.

               As the armature moves forward due to magnetic attraction the contact spring moves away from the contact screw. This breaks the circuit and the current stops flowing. As a result, the soft-iron core loses its magnetism. It, therefore, no longer attracts the armature which, then, is pulled back by the contact spring to its original position. As soon as the armature comes to its original position the electric circuit is again completed and the soft iron becomes magnetized. It again attracts the armature and thereby the hammer strikes against the gong and produces sound. As long as the push button remains pressed, the circuit is alternately broken and completed causing the hammer to strike the gong. Thus an electric bell keeps ringing.

               If a steel core is used instead of a soft-iron, then the steel core will become a permanent magnet due to passage of electric current through the winding. Consequently, the armature will stay attracted even when the contact spring moves away from the contact screw, so the hammer will strike the gong only once.

 

What is Osmosis?

               It is a well known fact that when resins are put in water they get swollen. This swelling takes place due to the entry of water through the membrane of the resins. Similarly, if grapes are put in sugar solution they shrink. Swelling of resins and shrinking of grapes take place due to a process known as osmosis. Do you know what this osmosis is?

               Osmosis is a process in which a solution of lower concentration passes into a solution of higher concentration through a semipermeable membrane. A semipermeable membrane is one that allows some, but not all, substances to pass through it. This contains very small pores. When resins are put into water, the covering acts as a semipermeable membrane. Water is less concentrated than the substance present inside the resins and so the water moves into the resins through its semipermeable membrane. Similarly, fluid from grapes moves out through the semipermeable membrane, as the concentration of sugar solution is more than that of the grapes. There is a tendency for solutions separated by a membrane to become equal in molecular concentration.

               In osmosis, the movement is always from a dilute solution into a solution of higher concentration. This reduces the concentration of the stronger solution. The rate of osmosis depends upon the comparative strengths of the two solutions. The greater the difference, the faster the rate of osmosis. This process continues until both solutions are of equal strength. When this equilibrium is reached, osmosis stops.

               Osmosis is an ongoing process among the living beings. The membranes of cells are semipermeable. Plants absorb water and dissolved minerals from the soil by osmosis; they use osmosis to move the water and dissolved minerals through the plant, cell by cell. Osmosis also maintains turgor pressure. Turgor pressure is the pressure of water on the cell. It gives the cell form and strength. When there is a decrease in turgor pressure, the plant will soon wilt and lose its regular stiffness.

               Osmosis allows the transfer of water and dissolved nutrients in the human body from the blood into the cells.