For a pure semiconductor, the Fermi level is
- In the valence band
- In the conduction band
- Well below the valence hand
- Near the center of the gap between the valence and conduction bands
Correct Option: (D)
The Fermi level is the energy level at which the probability of finding an electron is 50%.
The Fermi level for a pure semiconductor is near the center of the gap between the valence and conduction bands.
| Semiconductor type | Fermi level location |
|---|---|
| Intrinsic semiconductor | Near the center of the band gap |
| n-type semiconductor | Closer to the conduction band |
| p-type semiconductor | Closer to the valence band |
An acceptor replacement atom in silicon might have – – – electrons in its outer shell
- 3
- 4
- 5
- 6
Correct Option: (A)
An acceptor replacement atom in silicon has 3 electrons in its outer shell because it needs 1 more electron to complete its valence shell.
This electron will come from a neighboring silicon atom creating a hole in the valence band of the silicon atom.
Quarks are the constituents of
- All leptons
- All particles
- Only strange particles
- All strongly interacting particles
Correct Option: (D)
Quarks are the constituents of all strongly interacting particles.
Nuclear fusion in the Sun is increasing its supply of
- Helium
- Nucleons
- Positrons
- Hydrogen
Correct Option: (A)
Nuclear fusion in the Sun is decreasing its supply of hydrogen and increasing its supply of helium.
The hydrogen nuclei fuse together to form helium nuclei releasing a tremendous amount of energy.
A three-dimensional array of points each of which has identical surroundings is called a
- Motif
- Unit cell
- Space lattice
- Lattice points
Correct Option: (B)
A three-dimensional array of points each of which has identical surroundings is called a unit cell.
Which of the following is not a property of crystalline solids
- Isotropy
- Anisotropy
- Definite geometry
- Sharp melting point
Correct Option: (A)
The space lattice of a diamond is fcc. The primitive basis has two identical atoms at
- \( 000, \frac{1}{2}\frac{1}{2}0 \)
- \( 000, \frac{1}{4}\frac{1}{4}\frac{1}{4} \)
- \( 000, \frac{1}{2}\frac{1}{2}\frac{1}{2} \)
- \( 000, \frac{1}{4}\frac{1}{4}\frac{3}{4} \)
Correct Option: (B)
A relation between the surface integral of a vector and the volume integral of a derivative of the vector is
- Gauss’ law
- Stoke’s theorem
- Gauss’s theorem
- Convolution theorem
Correct Option: (C)
A relation between the surface integral of a vector and the volume integral of a derivative of the vector is Gauss’s theorem.
\[ \oint_{S}^{} \overrightarrow{A} .\overrightarrow{ds} = \oint_{V}^{} (\overrightarrow{\nabla } . \overrightarrow{A})dV \]
The effective mass is used to measure the
- Barrier concentration
- Carrier concentration
- Fermi energy
- None of these
Correct Option: (B)
The effective mass is used to measure the carrier concentration.
If the resistivity (Ω-cm) is in the range of 108 to 1020 then the material is a
- Insulator
- Conductor
- Semiconductor
- Superconductor
Correct Option: (A)
A material with resistivity in the range of 108 to 1020 Ω-cm is an insulator.
Insulators are materials that do not allow electrons to flow easily. They have a very high resistivity which means that a large amount of voltage is required to create a small current.