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

Which of the energy band diagrams shown in the figure corresponds to that of a semiconductor?

1.		2.
3.		4.

The energy band diagrams for three semiconductor samples of silicon are as shown. We can then assert that-

1. Sample X is undoped while samples Y and Z have been doped with a third group and a fifth group impurity respectively
2. Sample X is undoped while both samples Y and Z have been doped with a fifth group impurity
3. Sample X has been doped with equal amounts of third and fifth group impurities while samples Y and Z are undoped
4. Sample X is undoped while samples Y and Z have been doped with a fifth group and a third group impurity respectively

The temperature (T) dependence of resistivity ($\rho$) of a semiconductor is represented by