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KrishnaBalaram1235
30.03.2020 •
Physics
We can look at the band structure of an element to get an idea of how many electronsper atom participate in conduction. We can also determine this numberbased on the free electron density, the atomic mass, and the mass density of thematerial.Calculate the free electron density of lithium. The Fermi energy is 4.72 eV.
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Ответ:
the free electron density of lithium is 2.3 × 10²⁸ /m³
Explanation:
The Fermi energy is 4.72 eV.
The Fermi energy (highest filled orbital energy ) of free electron is
Rearrange the above equation for free electron density of lithium
where,
h = 6.626 × 10⁻³⁴J.s
Thus, the free electron density of lithium is 2.3 × 10²⁸ /m³
Ответ:
a) r₁ = 3.4565 10⁸ m , b)
= 3.661 10⁷ m
, c)
= 3.39 10⁸ m
Explanation:
a) For this exercise we will use Newton's second law where the forces are of gravitational attraction
F = G m M / r²
Let's locate the point where the forces are equal and from here we know which way they are greater
F₁ - F₂ = 0
F₁ is the force of attraction from Earth and F₂ the force of attraction from the Moon, let's use the subscript "e" for the Earth and the subscript "m" for the Moon
G m
/ r₁² = G m
/ r₂²
Let's measure the distance from the same reference system, which we will place in the center of the Earth
r₁ = r₁
r₂ = D - r₁
Where D is the distance from beats to the Moon, substitute
r₁ / D-r₁ = √
/ ![M_{m}](/tpl/images/0438/0384/f10c9.png)
r₁ / D-r₁ = √ (5.98 1024 / 7.36 1022) = 9.0139
r₁ = 9.0139 (D -r₁)
r₁ (1+ 9.0139) = 9.0139 D
r₁ = 9.0139 / 10.0139 D
r₁ = 0.9001 3.84 10⁸
r₁ = 3.4565 10⁸ m
It is this point sides forces are equal for greater distances the force of the moon exceeds the attraction of the Earth
b) The radius of the moon is
The distance measured from the Moon is
r₂ = D -r₁
r₂ = 3.84 108 - 3.4565 108
r₂ = 0.3835 108 m
r₂ = 3.835 107 m
The distance r₂ is measured from the center of the Moon, the distance measured from the surface is
c) The distance from the Earth's surface is