How the electronics era is evolved?

It’s being great news for all physics aspirants and also to the students and enthusiasts of electronics and tele-communication engineering students to know about the evolution of electronics subject. We should know it  first of all. As electronics is separate branch of physics which means that it is total new branch deals with the study of devices based on the controlled flow of electrons. It means these devices the flow of electrons can be controlled in the nature. On the basis of the electronics subject, there are two sub branches. 

They are vaccum tube electronics and semi conductor electronics. Now, let’s discuss with the vaccum electronics. In it, there is controlled flow of current by controlling the voltage in the devices. The devices are bulky. These are also called as valves because of uni-directional flow of current in them.  It is awesome work. There are many kinds of vaccum tubes. The type and name is based on the number of grids taken to manufacture the valve tube. They are diode valve, triode, tetrode, pentode, etc., In each type of vaccum tube there are two common plates called cathode and anode (plate).  Now, the triode valve is made up of three electrodes. These are one cathode, anode and other one is controlling grid. The grid is responsible for the controlled motion of the electrons from cathode to anode. The tetrode is made of anode, cathode and two grids.

The two grids are taken on the basis of the name suggest. Apart from the working, there are a lot of  disadvantages. They are bulk in size, require large amount of voltage about 100V, consume more power, very expensive, hard to handle and less reliable. There are a lot of amazing things regarding to the vaccum tubes. Due to such a large number of disadvantages, the vaccum tubes or valves had failed to put their impact after 1948. After 1948, the era of semiconductor electronics devices had arrived. All the disadvantages of semiconductors are taken around. The semiconductor electronics is the sub  branch of electronics which deals with the study of the devices based on the controlled flow of current. As a result a large number of devices had evolved after 1948. 

They are diode, SCR, transistor and integrated circuits, etc., There are many advantages of semiconductor devices against the disadvantage of valves or vaccum tubes. They are small in size, inexpensive, easy to use, require very less amount of voltage I,e, less than 12 V to work, consume very low power, did not dissipate the energy, easy to handle, more life and greater reliability of life. There are many other advantages against disadvantages to the vaccum tubes or valves which are responsible to make a great change in the era of electronics. It is awesome work and branch of physics. Due to  the evolution of electronics, the life of person had totally changed. We all know about the small gadgets like mobiles, TV.,

How we measure large distances?

Large distances such as the distance of a planet or a star from the earth cannot be measured directly with a metre scale. An important method in such cases is the parallax method. For the objects nearer than about 20 metres, we have the ability to distinguish their relative distances. The brain does this by using the fact that each of our two eyes sees objects from a slightly different point  of view. Close, or cover, your eyes alternately and observe this difference. The position of nearby objects relative to more distant objects is different for each eye. This difference, due to different view points is called parallax.

The brain process these two images, translating the parallax differences into a sensation of depth, solidity, and relative location of objects in space. This process is called stereoscopic vision. While stereoscopic parallax gives very good relative location of objects in space. Our brain is easily fooled when good relative distance information, we look at an object of unknown size against a featureless background. 

We also use parallax in another way. When we move about, our eyes see our surroundings from a continually changing point of view. This provides the brain with additional depth information, and is particularly striking when we observe a scene from a moving vehicle. 

The amount of shift is proportional to the ratio between the separation of the observation stations and the distance to object. There is formula of ta trigonometric parallax distance. 

There are number of methods to measure the large distances. they are:

1. Echo Method

2. SONAR

3. RADAR

4. Determination of height of inaccessible object