PN Junction diode is a semiconductor is made by combination of a low doped p-type and an n-type semiconductor. zener diode is also made similarly but with highly doped semiconductor because of which similarity between both the semiconductor is that they work similarly in forward bias nut in reverse bias, PN is a total insulator and zener can act normal after passing of zener voltage. Because of the reason that highly doped p-type and n-type semiconductor are used for constructing zener diode...

According to Rutherford atomic model, electron revolves around the positively charged nucleus. According to the electrodynamics, when any charged particles accelerated in the influence of other charged particles,then it loss the energy and emit the radiation. If it is so, the path of energy around nucleus will be spiral and electron will finally falls at the nucleus, ultimately size of atom gets collapsed. Fortunately,atom can't be destroyed.

Therefore, it does not explain about stability of...

Since only emitter-base portion or collector-base portion has to be used to use transistor as a rectifier. As base is thin and lightly doped, either of the two portions will not work as a p-n junction. Hence a transistor cannot be used as a rectifier.

The repeated use of NAND or NOR gates alone can give all other gates like OR, AND and NOT gates. In digital circuits the NAND or NOR gates serves as building blocks and hence they are named so.