© Subham Ram. Powered by Blogger.

Wednesday, February 26, 2014

Checking my blog

Posted by Subham  |  No comments

Checking how it looks after posting a blog.
So here its a sample article.

Devices in which a controlled flow of electrons can be obtained are the basic building blocks of all the electronic circuits. Before the discovery of transistor in 1948, such devices were mostly vacuum tubes (also called valves) like the vacuum diode which has two electrodes, viz., anode (often called plate) and cathode; triode which has three electrodes – cathode, plate and grid; tetrode and pentode (respectively with 4 and 5 electrodes).
In a vacuum tube, the electrons are supplied by a heated cathode and the controlled flow of these electrons in vacuum is obtained by varying the voltage between its different electrodes. Vacuum is required in the
inter-electrode space; otherwise the moving electrons may lose their energy on collision with the air molecules in their path. In these devices the electrons can flow only from the cathode to the anode (i.e., only in one direction). Therefore, such devices are generally referred to as valves. These vacuum tube devices are bulky, consume high power, operate generally at high voltages (~100 V) and have limited life and low reliability.
The seed of the development of modern solid-state semiconductor electronics goes back to 1930’s when it was realised that some solid state semiconductors and their junctions offer the possibility of controlling the number and the direction of flow of charge carriers through them. Simple excitations like light, heat or small applied voltage can change the number of mobile charges in a semiconductor. Note that the supply and flow of charge carriers in the semiconductor devices are within the solid itself, while in the earlier vacuum tubes/valves, the mobile electrons were obtained from a heated cathode and they were made to flow in an
evacuated space or vacuum. No external heating or large evacuated space is required by the semiconductor devices. They are small in size, consume low power, operate at low voltages and have long life and high reliability.
Even the Cathode Ray Tubes (CRT) used in television and computer monitors which work on the principle of vacuum tubes are being replaced by Liquid Crystal Display (LCD) monitors with supporting solid state
electronics. Much before the full implications of the semiconductor devices was formally understood, a naturally occurring crystal of galena (Lead sulphide, PbS) with a metal point contact attached to it was used as detector of radio waves.

4:13:00 AM Share:
About Subham Ram

Subham is an undergraduate student pursuing his studies in IT. He is a curious fellow who wants to know everything about everything except somethings. He loves learning web-designing, singing, reading novels and a little bit of writing. Follow him on Twitter.

0 comments:

Get updates in your email box
Complete the form below, and we'll send you the best coupons.

Deliver via FeedBurner

Kolkata Bloggers

Tweets by Subham

Recent News

About Us

This is a personal blog of Subham who writes here to help others with tech-solutions or to express himself. So here 'US' consists of Subham only. This blog is purely a work of emotion driven writing except the technology posts. Thanks for visiting.
Proudly Powered by Blogger. ® All Rights Reserved.
back to top