Indian Institute of Technology Joint Entrance Exam (IIT-JEE),organized and conducted by IITs attracts the brightest minds of the nation every year and is attended by lakhs of students who aspire to get admission in Engineering and Technology. Getting admitted into the IITs is often considered the height of accomplishment due to high standards of the examination.IITs were first conceived by then prime minister Jawaharlal Nehru in 1950s as part of his vision to promote the growth of science and technology in India.
Phenomenon of superconductivity was first observed by Kamerlingh Onnes in Leiden in 1911 ,3 years after he first liquified helium gas. He observed that electrical resistivity of such as mercury, tin, lead completely disappear i.e., suddenly dropped to zero in a small range of temperature at a critical temperature TC which is the characterstics of the material.
Many materials like carbon can exist in various forms for example it can exist as diamond in solid form and graphite is also one form of carbon and clearly dimond and graphite have different mechanical, thermal, optical and electrical properties. These properties of different forms of carbon can be understood in terms of carbon atoms in the solid structure.
When a PN junction is reversed biased it allows very small current to flow through it. This current is due to the movement of minority charge carriers and it is almost independent of the voltage applied.
If reverse bias is made too high, the current through PN junction increases abruptly and the voltage at which this phenomenon occurs is called breakdown voltage .