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sukhopar [10]
3 years ago
15

(a) The lattice constant of GaAs is 5.65 Å. Determine the number of Ga atoms andAs atoms per cm 3 .

Engineering
1 answer:
Natasha_Volkova [10]3 years ago
7 0

Answer:

a) Number of atoms per unit cell for Ga = 4 atoms per unit cell

Number of atoms per unit cell for As = 4 atoms per unit cell

b) Volume density of Germanium in its unit cell = 4.35 × 10²² /cm³

Explanation:

GaAs has a number density of 4.42 x 10²² atoms/cm³ from literature.

Since GaAs is known to contain almost equal amounts of Ga and As.

Number density of Ga = Number density of As = 2.21 × 10²² atoms/cm³

Number density = Number of atoms in a unit cell/volume of the unit cell

Number of atoms in the unit cell = ?

Volume of the unit cell = (lattice parameter)³ = (5.65 × 10⁻⁸)³ = 1.804 × 10⁻²² cm³

Number of atoms per unit cell for Ga and As = number density × volume of unit cell = 2.21 × 10²² × 1.804 × 10⁻²² = 4 atoms/unit cell

b) Volume density = Number of atoms per unit cell/volume of unit cell

Germanium has 8 atoms per unit cell (from literature),

Volume of unit cell = (lattice parameter)³ = (5.65 × 10⁻⁸)³ = 1.804 × 10⁻²² cm³

Volume density = 8/(1.804 × 10⁻²²) = 4.35 × 10²² /cm³

Hope this helps!

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REY [17]

Answer:

0.5°c

Explanation:

Humidity ratio by mass can be expressed as

the ratio between the actual mass of water vapor present in moist air - to the mass of the dry air

Humidity ratio is normally expressed in kilograms (or pounds) of water vapor per kilogram (or pound) of dry air.

Humidity ratio expressed by mass:

x = mw / ma                                  (1)

where

x = humidity ratio (kgwater/kgdry_air, lbwater/lbdry_air)

mw = mass of water vapor (kg, lb)

ma = mass of dry air (kg, lb)

It can be as:

x = 0.005 (100) / [(100 - 100)]

x = 0.005 x 100 / (100 - 100)

x = 0.005 x 100 / 0

x = 0.5°c

So the temperature to which atmospheric air must be cooled in order to have humidity ratio of 0.005 lb/lb is 0.5°c

6 0
3 years ago
Twenty-five wooden beams were ordered or a construction project. The sample mean and he sample standard deviation were measured
aksik [14]

Answer:

Correct option: B. 90%

Explanation:

The confidence interval is given by:

CI = [\bar{x} - z\sigma_{\bar{x}} , \bar{x}+z\sigma_{\bar{x}} ]

If \bar{x} is 190, we can find the value of z\sigma_{\bar{x}}:

\bar{x} - z\sigma_{\bar{x}}  = 188.29

190 - z\sigma_{\bar{x}}  = 188.29

z\sigma_{\bar{x}}  = 1.71

Now we need to find the value of \sigma_{\bar{x}}:

\sigma_{\bar{x}} = s / \sqrt{n}

\sigma_{\bar{x}} = 5/ \sqrt{25}

\sigma_{\bar{x}} = 1

So the value of z is 1.71.

Looking at the z-table, the z value that gives a z-score of 1.71 is 0.0436

This value will occur in both sides of the normal curve, so the confidence level is:

CI = 1 - 2*0.0436 = 0.9128 = 91.28\%

The nearest CI in the options is 90%, so the correct option is B.

4 0
4 years ago
A rigid tank whose volume is 2 m3, initially containing air at 1 bar, 295 K, is connected by a valve to a large vessel holding a
bazaltina [42]

Answer:

Q_{cv}=-339.347kJ

Explanation:

First we calculate the mass of the aire inside the rigid tank in the initial and end moments.

P_iV_i=m_iRT_i (i could be 1 for initial and 2 for the end)

State1

1bar*|\frac{100kPa}{1}|*2=m_1*0.287*295

m_1=232kg

State2

8bar*|\frac{100kPa}{1bar}|*2=m_2*0.287*350

m_2=11.946

So, the total mass of the aire entered is

m_v=m_2-m_1\\m_v=11.946-2.362\\m_v=9.584kg

At this point we need to obtain the properties through the tables, so

For Specific Internal energy,

u_1=210.49kJ/kg

For Specific enthalpy

h_1=295.17kJ/kg

For the second state the Specific internal Energy (6bar, 350K)

u_2=250.02kJ/kg

At the end we make a Energy balance, so

U_{cv}(t)-U_{cv}(t)=Q_{cv}-W{cv}+\sum_i m_ih_i - \sum_e m_eh_e

No work done there is here, so clearing the equation for Q

Q_{cv} = m_2u_2-m_1u_1-h_1(m_v)

Q_{cv} = (11.946*250.02)-(2.362*210.49)-(295.17*9.584)

Q_{cv}=-339.347kJ

The sign indicates that the tank transferred heat<em> to</em> the surroundings.

8 0
3 years ago
Consider this example of a recurrence relation. A police officer needs to patrol a gated community. He would like to enter the g
SashulF [63]

Answer:

the police officer cruise each streets precisely once and he enters and exit with the same gate.

Explanation:

NB: kindly check below for the attached picture.

The term ''Euler circuit'' can simply be defined as the graph that shows the edge of K once in a finite way by starting and putting a stop to it at the same vertex.

The term "Hamiltonian Circuit" is also known as the Hamiltonian cycle which is all about a one time visit to the vertex.

Here in this question, the door is the vertex and the road is the edge.

The information needed to detemine a Euler circuit and a Hamilton circuit is;

"the police officer cruise each streets precisely once and he enters and exit with the same gate."

Check attachment for each type of circuit and the differences.

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3 years ago
Need help solving math problem using integration
notka56 [123]
Ummm did you try to add or subtract and multiply or divide that can get your answer
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2 years ago
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