Let ${\mathrm{n}}_{\mathrm{P}}$ and ${\mathrm{n}}_{\mathrm{e}}$ be the number of holes and conduction electrons respectively in a semiconductor. Then

(1) ${\mathrm{n}}_{\mathrm{P}}$>${\mathrm{n}}_{\mathrm{e}}$ in an intrinsic semiconductor

(2) ${\mathrm{n}}_{\mathrm{P}}$=${\mathrm{n}}_{\mathrm{e}}$ in an extrinsic semiconductor

(3) ${\mathrm{n}}_{\mathrm{P}}$=${\mathrm{n}}_{\mathrm{e}}$ in an intrinsic semiconductor

(4) ${\mathrm{n}}_{\mathrm{e}}$<${\mathrm{n}}_{\mathrm{P}}$ in an intrinsic semiconductor

Wires P and Q have the same resistance at ordinary (room) temperature. When heated, resistance of P increases and that of Q decreases. We conclude that

(1) P and Q are conductors of different materials

(2) P is N-type semiconductor and Q is P-type semiconductor

(3) P is semiconductor and Q is conductor

(4) P is conductor and Q is semiconductor

In P-type semiconductor the majority and minority charge carriers are respectively

(1) Protons and electrons           

(2) Electrons and protons
(3) Electrons and holes               

(4) Holes and electrons

In a semiconductor the separation between conduction band and valence band is of the order of

(1) 100 eV                     

(2) 10 eV
(3) 1 eV                         

(4) 0 eV

When N-type of semiconductor is heated

(a) Number of electrons increases while that of holes decreases

(b) Number of holes increases while that of electrons decreases

(c) Number of electrons and holes remains same

(d) Number of electrons and holes increases equally

In case of a semiconductor, which of the following statement is wrong 

(1) Doping increases conductivity

(2) Temperature coefficient of resistance is negative

(3) Resisitivity is in between that of a conductor and insulator

(4) At absolute zero temperature, it behaves like a conductor

 In a P-type semiconductor, germanium is doped with

(1) Boron                     

(2) Gallium
(3) Aluminium             

(4) All of these

Which is the correct relation for the forbidden energy gap in the conductor, semiconductor, and insulator

(1) $∆{\mathrm{Eg}}_{\mathrm{c}}<∆{\mathrm{Eg}}_{\mathrm{insulator}}<∆{\mathrm{Eg}}_{sc}$
(2) $∆{\mathrm{Eg}}_{\mathrm{c}}<∆{\mathrm{Eg}}_{\mathrm{sc}}<∆{\mathrm{Eg}}_{\mathrm{insulator}}$
(3) $∆∆{\mathrm{Eg}}_{\mathrm{sc}}<∆{\mathrm{Eg}}_{\mathrm{insulator}}<{\mathrm{Eg}}_{\mathrm{c}}$
(4) $∆{\mathrm{Eg}}_{\mathrm{sc}}<∆Ec<∆{\mathrm{Eg}}_{\mathrm{insulator}}$

Which of the following has negative temperature coefficient of resistance 
(1) Copper               

(2) Aluminium
(3) Iron                   

(4) Germanium

The energy gap of silicon is 1.14 eV. The maximum wavelength at which silicon will begin absorbing energy is

(1) 10888 Å                   

(2) 1088.8 Å
(3) 108.88 Å                   

(4) 10.888 Å