question_answer

Fill in the blanks using the word(s) from the list appended with each statement: (i) As the temperature rises, the resistance offered by metals ___ (increases, decreases) (ii) The conduction band of an insulator is ___ empty, (partially, practically) (iii) The semiconductors are ___ at absolute zero. (conductors, insulators) (iv) The resistance of semiconductors ___ with increasing temperature, (decreases, increases) (v) The forbidden energy gap in case of a semiconductor is ___ as compared to that of an insulator, (smaller, greater) (vi) In an intrinsic semiconductor, the electron and hole concentrations are ___ (equal, unequal) (vii) When a block of semiconductor is connected to a battery by a metallic wire, the current flow in the wire is due to the motion of ___ in the wire. (electrons, electrons and holes) (viii) The doping of an intrinsic semiconductor with certain type of impurity atoms causes a/an ___ in its electric conductivity. (decrease, increase) (ix) The movement of charge carriers from a region of higher concentration to a region of lower concentration is called ___ (drift, diffusion) (x) When a battery is connected to a p-type semiconductor with metallic wire, the current in the semi-conductor is predominantly due to ___ (electrons, holes) (xi) Thomson coefficient for a p-type semi- conductor is ___ (positive, negative) (xii) The drift velocity of electrons is expected to be ___ (equal to, greater than) that of holes. (xiii) When two isolated atoms are brought  close to each other such that the distance between them is ___ (comparable to, much larger than) lattice spacing, the ___ (energy bands, energy levels) of the outermost electrons are split into ___ (very large, very small) number of levels, called ___ (energy gap, energy bands). (xiv) The energy band in solids is an outcome of ___   (Pauli's   exclusion   principle, Coulomb's law).

Answer:

                    (i) increases, (ii) partially, (iii) insulators, (iv) decreases, (v) smaller, (vi) equal, (mi) electron, (viii) increase, (ix) diffusion, (x) holes, (xi) negative, (xii) greater than, (xiii) comparable to, energy levels, very large, energy bands, (xiv) Pauli's exclusion principle.