Category Science

What makes Aristotle a giant among scientists?

Aristotle was one of the most respected Greek thinkers. He was the star pupil of Plato, a famous Greek philosopher. He was also the teacher of Alexander the great!

     Aristotle wrote on many subjects including physics, biology, zoology, meta-physics, logic, ethics, aesthetics, poetry, theatre, music, rhetoric, linguistics, politics, and government.

        He believed that the universe was eternal, that there was neither a beginning nor an end. Aristotle accepted that things can change, but fundamentally believed that the overall conditions would always remain the same. He studied zoology very closely, and through careful observation, he was able to arrive at his conclusions. His careful study of animals enabled him to classify them into different groups and species.

     Aristotle’s influence on western culture and science has been enormous. His writings show him to be a man of tremendous intellect, who thought deeply about the world.

 

Why Hippocrates is called the ‘father of western medicine’?

Hippocrates, a Greek physician, lived in the 5th century BC, and founded the Hippocratic School of medicine. He revolutionized Greek medicine, for he believed in, and developed the practice of the clinical method of observation. This was the careful nothing of all the symptoms of a disease, and of the changes in a patient’s condition during the illness.

       Hippocrates believed that the body must be treated as a whole. He made medicine a discipline distinct from other fields, and his biggest contribution was that he rejected superstition and the belief that supernatural, or divine forces, were the cause of illness.

       In short, it was Hippocrates who transformed medicine into a science. He wrote on a variety of medical topics including diagnosis, epidemics, obstetrics, paediatrics, nutrition and surgery.

       To this day, newly qualified doctors take an oath called the Hippocratic Oath that lays down the basic rules of conduct that doctors must follow.

 

Why Pythagoras is considered one of the greatest scientists of all time?

Pythagoras was an ancient Greek mathematician and philosopher who lived more than 500 years before Christ.

        He spent most of his life in the Greek colonies in Sicily and southern Italy. He was also a philosopher, and founder of the religious movement called Pythagoreans.

        Pythagoras had a group of disciples who followed him around, and taught other people what he had taught them. He made crucial contributions to modern philosophy, as well as mathematics, science, and religious mysticism. It is also believed that he had a significant influence on medicine, music, astronomy, and divination.

        Pythagoras is best known for the mathematical theory named after him. He is without doubt, one of the greatest scientists not only of the ancient world, but of all time.

How does a cordless phone work?

The cordless phone is an FM transmitter/receiver. The frequency range lies between 26.6 and 49.8 MHz A cordless phone essentially converts the audio signals from the telephone line into the FM waves and it is detected by the mobile handset, and vice versa. For security reasons the range is limited to about 100 metres and their power is about 500 milliwatts. Each cordless phone is assigned a particular channel (or frequency range) to avoid interference with nearby instruments. 

Cordless phone is based on wireless transmission and frequency modulation. The main components of a cordless phone are the base unit and the portable unit. While the base unit is kept at a fixed point, connected to power supply and the working telephone line, the portable unit can be carried to a certain distance, depending on the frequency range limitation. Normally in India, the permissible distance is about 100 metres.

 The base unit and the portable unit essentially consist of radio wave transmission and reception devices which enable a two way wireless communication between these units.

The radio waves are broadcast in the air through the antenna fitted to the units. Just like the signals emanating from the telephone are converted to radio frequency in the transmission side, the reverse happens in the receiver side, (i.e.) the radio frequency signals are converted into original signals, bell or speech.

 Since the handset does not have and connecting cord or wire, the name cordless phone.

            

How does a cell phone work?

    In normal telephone exchange systems, a pair of wires extends each telephone instrument to the telephone exchange.

Normally, copper conductors are used to give loop to indicate the exchange that the telephone hand set had been lifted for making a call or for receiving a call. In advanced countries, Optical Fibre is also used or for extending the loop.

When you make a call to your friend who is connected to another exchange, the digits are sent to the exchange to which you are connected, in the form of pulses (break and make of loop) or frequencies.

The originating exchange analyses these digits and establishes a path to the terminating exchange where your friend is connected. Over this path, signals (some of the digits dialed by you and other technical information) are sent in the form of bits or frequencies. 

The terminating exchange analyses and marks your friend’s line and if it is free, a ring is sent to him and ring back tone is sent to you. When the call is answered, metering takes place.

In the cell phone system, there is no permanent wire connection between the instrument and the mobile telephone exchange. The connection between the instrument and mobile exchange is established via an intermediate station called Base Station (BS) where a transmitting tower is erected. The connectivity between the mobile exchange and the BS may be wire and between BS and Cell Phone is a Radio Channel.

The connection between a mobile exchange and another mobile exchange or public telephone exchange is by wire.

 Cell phones are technically called Mobile Station (MS) and its telephone exchange is called Mobile Switching Centre (MSC). The radio channel for both-way voice and control channel for controlling are established between BS and MS whenever required only.                                

A town or an area is divided into smaller areas called Cells. At the centre of the cell, there exists the Base Station (BS). When the MS moves around inside the cell, the signals including voice will be strong. When you use a cell phone to talk to your friend with conventional phone, you will   be connected to the BS over a booth-way Radio channel. From BS to MSC over a copper cable or Optic Fibre cable, from MSC to another Exchange and further to your friend over a copper cable

            As you are moving and when you enter into another cell, old BS reports to MSC that you have left the cell and your signals are weak. Immediately, the MSC orders all other Base stations to search for a new comer (as far as other cells are concerned, you are a new comer).

 The BS which is very near to you reports to the MSC that it has found a new corner with strong signals. The MSC orders the old BS to hand off (you) to new BS. Handing off is done in less than 400 milliseconds. But you do not feel any disturbance in your conversation. You may cross many cells during your long conversation without knowing that so many hands off have taken place. Each cell phone is associated with a unique identity stored in Subscriber Identity Module (SIM). This identity is sent to MSC through Base Station when ‘Send’ button is pressed.

The MSC analyses this and validates as to whether cell phone is authorized to make a call. If yes, the call will be put through. When there is an incoming call to the MS, first it is received by the MSC. MSC analyses the received information that contains the MS number also. This number is paged in all cells. If the MS is kept powered on, a page response is received on the control channel from the MS. A voice channel is allotted by MSC. BS and MS are ordered to tune to that channel. Once tuned through connection information is returned to the caller who gets ring-back tone. Ringing is initiated in the MS. When the MS answers, conversation can start and metering starts in MSC.

Why satellites are always launched from the east coast?

         Earth rotates from west to east causing the Sun, the Moon, stars and other planets rise from east and set in the west. On the surface of the earth each point is moving eastward with respect to an astronaut in space.

            Thus if a rocket is launched at a small angle eastward vertically the speed of earth gets added to the rocket’s speed. This reduces the amount of fuel required. If the rocket is inclined along any other direction, the speed of the earth gets subtracted from the speed of rocket and will necessitate burning of more fuel.

            In addition, in case of any failure during launch the rocket will fall back to the earth. Hence if it is launched from the east coast, the rocket will fall into the sea only. If it is launched from the west coast, in case of failure, the rocket will fall on the land endangering human habitats. Thus choosing eastward inclination is scientific but choice of eastern coast concerns safety.