Energy Bands in Solids

Energy Bands in Solids

• (a)valance band is partially empty and the conduction band is partially filled.
• (b)valance band is completely filled and the conduction band is partially filled.
• (c)valance band is completely filled.
• (d)conduction band is completely empty.

Energy Bands in Solids

• (a)exactly zero
• (b)extremely large
• (c)extremely small
• (d)sometimes small and sometimes large

Energy Bands in Solids

• (a)very high, empty
• (b)very low, empty
• (c)very high, completely filed
• (d)very low, partially filled

Energy Bands in Solids

• (a)have large forbidden energy gap.
• (b)have overlapping valence and conduction bands.
• (c)are full of electrons.
• (d)have no valence band.

Energy Bands in Solids

• (a)the valence band is completely filled and the conduction band partially filled.
• (b)the valence band is completely filled.
• (c)the conduction band is completely filled.
• (d)the valence band is partially empty and the conduction band partially filled.

Energy Bands in Solids

• (a)the valence band is completely filled.
• (b)the conduction band is completely empty.
• (c)the conduction band is partially filled and the valence band is partially empty.
• (d)the valence band is completely filled and conduction band is partially empty.

Energy Bands in Solids

• (a)the valence band is completely filled
• (b)the conduction band is completely filled
• (c)the condition band is partially filled and valence band is partially empty
• (d)the valence band is completely filled and the conduction band is partially filled

Energy Bands in Solids

• (a)very low and partially filled.
• (b)very high and completely filled.
• (c)very high and empty.
• (d)very low and empty.

Energy Bands in Solids

• (a)valence band is empty and conduction band is filled with electrons.
• (b)conduction band is empty and valence band is completely filled with electrons.
• (c)valence band is partially filled.
• (d)conduction band is partially filled with electrons.

Energy Bands in Solids

• (a)Germanium
• (b)Silver
• (c)Glass
• (d)Silicon

Energy Bands in Solids

• (a)valance band and conduction band overlap each other.
• (b)valance band and conduction band are separated by large energy gap.
• (c)valancè band and conduction band are separated by a small energy gap.
• (d)a very small number of electrons are available for electrical conduction.

Energy Bands in Solids

• (a)is separated by large energy gap.
• (b)is separated by small energy gap:
• (c)is almost empty.
• (d)overlap each other.

Energy Bands in Solids

• (a)very high empty.
• (b)very low, partially filled
• (c)very high, completely filled
• (d)very low, empty.

Energy Bands in Solids

• (a)Generally, in conductors the valence and conducting bands overlap.
• (b)The resistivity of a semiconductor increases with increase in temperature
• (c)The conductivity of a semiconductor increase with increase in temperature
• (d)Substances with energy gap of the order of $10\text{ eV}$ are insulators

Energy Bands in Solids

• (a)In case of C the valence band is not completely filled at absolute zero temperature.
• (b)In case of C the conduction band is partly filled even at absolute zero temperature.
• (c)The four bonding electrons in the case of C lie in the second orbit, whereas in the case of Si they lie in the third.
• (d)The four bonding electrons in the case of C lie in the third orbit, whereas for Si they lie in the fourth orbit.

Energy Bands in Solids

• (a)The number of free electrons for conduction is significant only in $\text{Si}$ and $\text{Ge}$ but small in $\text{C}.$
• (b)The number of free conduction electrons is significant in $\text{C}$ but small in $\text{Si}$ and $\text{Ge}.$
• (c)The number of free conduction electrons is negligibly small in all the three.
• (d)The number of free electrons for conduction is significant in all the three

Energy Bands in Solids

• (a)All $E_c, E_g, E_v$ increase
• (b)$E_c$ and $E_v$ increase, but $E_g$ decreases
• (c)$E_c$ and $E_v$ decrease, but $E_g$ increases
• (d)All $E_c, E_g, E_v$ decrease

Energy Bands in Solids

• (a)In conductors the valence and conduction bands overlap.
• (b)Substances with energy gap of the order of 10 eV are insulators.
• (c)The resistivity of a semiconductor increases with increase in temperature.
• (d)The conductivity of a semiconductor increases with increase in temperature.

Energy Bands in Solids

• (a)(Eg)C > (Eg)Si
• (b)(Eg)C < (Eg)Si
• (c)(Eg)C = (Eg)Si
• (d)(Eg)C < (Eg)Ge.

Energy Bands in Solids

• (a)$2.5\text{ eV}$
• (b)$1.1\text{ eV}$
• (c)$0.7\text{ eV}$
• (d)$0.5\text{ eV}$

Energy Bands in Solids

• (a)Bohr's correspondence principle
• (b)Pauli's exclusion principle
• (c)Heisenberg's uncertainty principle
• (d)Boltzmann's law

Energy Bands in Solids

• (a)the valence band is partially empty and the conduction band is partially filled
• (b)the valence band is completely filled and the conduction band is partially filled
• (c)the valence band is completely filled
• (d)the conduction band is completely empty

Energy Bands in Solids

• (a)metals
• (b)superconductors
• (c)insulator
• (d)semiconductor