The probability that a state which is 0.2eV above the fermi energy in a metal atom at 700K is?
E  E_{f }= 0.2 eV
k_{B} = 8.62 x 10^{5 }eVK^{1}
T = 700K
P = 0.036
The correct answer is: 0.036
Be has hexagonal closed packed structure with smaller lattice parameter equal to 2.29. Concentration of electron in Be crystal is in terms of 10^{29} m^{3} .
Here a = 2.29
for hexagonal close packing
There are two atoms in primitive cell and each atom carries 4 electrons.
The correct answer is: 8.15
A copper wire of uniform crosssectional area 10 x 10^{6} m^{2} carries a current of 1 Assuming that each copper atom contributes one electron to the electron gas, the drift velocity of free electron in units of µm/sec is :
of copper is 8.94 x 10^{3} kg/m^{3} and its atomic mass is 1.05 x 10^{25} kg).
The correct answer is: 74
Consider a crystal of fee structure. The density of the crystal is 8.96 glcm^{3} and atomic weight is 63.5. Then what is the lattice constant for the crystal (in )?
Lattice constant
The correct answer is: 3.61
The distance between the adjacent atomic planes in CaCO_{3} is 0.3 nm. The smallest angle of Bragg scattering for 0.03 nm X ray is (in degrees)
 For constructive interference, we must have
2dsinθ=nλ
sinθ=nλ/2d
=1×0.3×10^{−10} / 2×0.3×10^{9}
=0.05rad
or
=0.05×180/π = 2.86degree
Sodium contains 2.54 x10^{22} free electrons per cm^{3} ( given = 6.63 x 10 ^{34} Js, m= 9 .11 x 10^{31} kg , k_{B} = 1.38 x 10^{23 }JIK and 1eV = 1.6 x 10^{19 }J ) , then Fermi D 4 temperature is given in terms of 10^{4} K as?
We know that
⇒
The correct answer is: 3.6
In a powder diffraction pattern recorded from a facecentred cubic sample using X rays. The first peak appears at 30°. The second peak will appear at what angle (degrees)
For 2nd peak [2 0 0],
The correct answer is: 35.3
Masses of ionic radii of Na^{+} and CI^{– }in NaCI^{ }crystals are 22.99 amu, 0.98A and 35.45 amu, 1.82A respectively. What is the packing fraction of NaCI?
Lattice parameter a =
a = 2 [0.98 + 1.82]
a = 5.6A
Each unit cell contains 4 atoms.
Packing fraction =
Packing fraction =
Packing fraction = 0.66
The correct answer is: 0.66
Given that density of sodium is 0.971 g/cm^{3} and atomic weight is 23. If h = 6.63 * 10¯^{34} Js, mass of electron = 9.11 x 10^{31} kg and Avogadro’s number is 6.02 x 10^{23} atoms/mol. Assuming each sodium atom contribute one electron to the electron gas. What is the electron density in units of 10^{28} Im^{3} ?
Electron density of sodium
The correct answer is: 2.54
Packing fraction of diamond cubic crystal structure is ____ % ?
Number of atoms in diamond crystal
Packing fraction
= 0.34
= 34%
The correct answer is: 34








