Question

(i) Distinguish between a conductor and a semi conductor on the basis of energy band diagram
(ii) The following figure shows the input waveforms (A, B) and the output waveform (Y) of a gate. Identify the gate, write its truth table and draw its logic symbol.

Answer 1

i) For a conductor, there is no gap in between the valence band and conduction band. Thus the band gap energy is almost zero for conductor. For a semiconductor, there is a small gap in between valence band and conduction band and so a semiconductor must have band gap energy.

ii) For this type of problem, we will first make the truth table according to the given waveform. The truth table is shown in figure and according to truth table, the gate is $\text{NAND}$ gate whose logic symbol is as shown in figure.