Solid State Physics MCQs Question and Answer in Engineering Physics

A. directly proportional to T above Debye temperature and to T³ below it

B. inversely proportional to T for all temperatures

C. independent of T for all temperatures

D. directly proportional to T above Debye temperature and to T⁵ below it

A. can never be positive

B. can never be negative

C. can be positive or negative

D. depends on its spin

A. The electrons and holes have different mobilities in a semiconductor

B. In an n-type semiconductor, the Fermi level lies closer to the conduction band edge

C. Silicon is a direct band gap semiconductor

D. Silicon has diamond structure

A. negative near the bottom of the band

B. a scalar quantity with a small magnitude

C. zero at the centre of the band

D. negative near the top of the band

A. retains its magnetic flux because the surface current supports it

B. expels out its magnetic flux because it behaves like a paramagnetic material

C. expels out its magnetic flux because it behaves like an antiferromagnetic material

D. expels out its magnetic flux because the surface current induces a field in the direction opposite to the applied magnetic field

A. its susceptibility is doubled when it is cooled from 300 K to 200 K

B. all the atomic magnets in it get oriented in the same direction above 100 K

C. the plot of inverse susceptibility versus temperature is linear with a slope T_c

D. the plot of its susceptibility versus temperature is linear with an intercept T_c

A. the slope of E versus k is proportional to the group velocity

B. the slope of E versus k has its maximum value at |k| = π/a

C. the plot of E versus k will be parabolic in the interval (-π/a) < k < (π/a)

D. the slope of E versus k is non-zero for all k the interval (-π/a) < k(π/a)

A. Dulong-Petit: $$C \propto \exp \left( {\frac{{ - a}}{T}} \right)$$   ; Einstein: C = constant; Debye: $$C \propto {\left( {\frac{T}{A}} \right)^3}$$

B. Dulong-Petit: C = constant; Einstein: $$C \propto {\left( {\frac{T}{A}} \right)^3}$$  ; Debye: $$C \propto \exp \left( {\frac{{ - a}}{T}} \right)$$

C. Dulong-Petit: C = constant; Einstein: $$C \propto \frac{{{e^{ - a/T}}}}{{{T^2}}}$$   ; Debye: $$C \propto {\left( {\frac{T}{A}} \right)^3}$$

D. Dulong-Petit: $$C \propto {\left( {\frac{T}{A}} \right)^3}$$  ; Einstein: $$C \propto \frac{{{e^{ - a/T}}}}{{{T^2}}}$$   ; Debye: C = constant

A. moves with the atoms in the optical mode and remains fixed in the acoustic mode

B. remains fixed in the optical mode and moves with the atoms in the acoustic mode

C. remains fixed in both optical and acoustic modes

D. moves with the atoms in both optical and acoustic modes

A. $$\overrightarrow {\bf{A}} = \frac{{2\pi }}{a}\left( {{\bf{\hat x}} - {\bf{\hat y}}} \right);\,\overrightarrow {\bf{B}} = \frac{{2\pi }}{a}\left( {{\bf{\hat y}} + {\bf{\hat z}}} \right);\,\overrightarrow {\bf{C}} = \frac{{2\pi }}{a}\left( {{\bf{\hat x}} + {\bf{\hat z}}} \right)$$

B. $$\overrightarrow {\bf{A}} = \frac{{2\pi }}{a}\left( {{\bf{\hat x}} - {\bf{\hat y}}} \right);\,\overrightarrow {\bf{B}} = \frac{{2\pi }}{a}\left( {{\bf{\hat y}} - {\bf{\hat z}}} \right);\,\overrightarrow {\bf{C}} = \frac{{2\pi }}{a}\left( {{\bf{\hat x}} + {\bf{\hat z}}} \right)$$

C. $$\overrightarrow {\bf{A}} = \frac{{2\pi }}{a}\left( {{\bf{\hat x}} + {\bf{\hat y}}} \right);\,\overrightarrow {\bf{B}} = \frac{{2\pi }}{a}\left( {{\bf{\hat y}} + {\bf{\hat z}}} \right);\,\overrightarrow {\bf{C}} = \frac{{2\pi }}{a}\left( {{\bf{\hat x}} - {\bf{\hat z}}} \right)$$

D. $$\overrightarrow {\bf{A}} = \frac{{2\pi }}{a}\left( {{\bf{\hat x}} + {\bf{\hat y}}} \right);\,\overrightarrow {\bf{B}} = \frac{{2\pi }}{a}\left( {{\bf{\hat y}} + {\bf{\hat z}}} \right);\,\overrightarrow {\bf{C}} = \frac{{2\pi }}{a}\left( {{\bf{\hat x}} + {\bf{\hat z}}} \right)$$