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Anika [276]
2 years ago
14

The electron concentration in silicon at T = 300 K is given by

Engineering
1 answer:
puteri [66]2 years ago
7 0

Answer:

E=1.44*10^-7-2.6exp(\frac{-x}{18} )v/m

Explanation:

From the question we are told that:

Temperature of silicon T=300k

Electron concentration n(x)=10^{16}\exp (\frac{-x}{18})

                                        \frac{dn}{dx}=(10^{16} *(\frac{-1}{16})\exp\frac{-x}{16})

Electron diffusion coefficient is Dn = 25cm^2/s \approx 2.5*10^{-3}

Electron mobility is \mu n = 960 cm^2/V-s \approx0.096m/V

Electron current density Jn = -40 A/cm^2 \approx -40*10^{4}A/m^2

Generally the equation for the semiconductor is mathematically given by

Jn=qb_n\frac{dn}{dx}+nq \mu E

Therefore

-40*10^{4}=1.6*10^{-19} *(2.5*10^{-3})*(10^{16} *(\frac{-1}{16})\exp\frac{-x}{16})+(10^{16}\exp (\frac{-x}{18}))*1.6*10^{-19}*0.096* E

E=\frac{-2.5*10^-^7 exp(\frac{-x}{18})+40*10^{4}}{1.536*10^-4exp(\frac{-x}{18} )}

E=1.44*10^-7-2.6exp(\frac{-x}{18} )v/m

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A proposed embankment fill requires 7100 ft of compacted soil. The void ratio of the compacted fill is specified as 0.5. Four bo
podryga [215]

Answer:

1) the volume of solid (Vs) is 4733.33 ft³

2) the total cost to pay Pit A is $58220

3) the total cost to pay to Pit B is $53344.67

4) the total cost to pay to Pit C is $34269.32

5) the total cost to pay to Pit D is $49132.02

Explanation:  

given the data in the question;

Vs = ?, V = 7100 ft³, e = 0.5

1) Calculate the volume of solid (Vs)

Vs = V / ( 1 + e )

we substitute

Vs = 7100 / ( 1 + 0.5 )

Vs = 7100 / 1.5

Vs = 4733.33 ft³

Therefore, the volume of solid (Vs) is 4733.33 ft³

2) Calculate the total cost to pay to Pit A

VpitA / Vcomp = ( 1 + e_{PHA}) / ( 1 + e_{comp )

we substitute

VpitA / 7100 = ( 1 + 1.5) / ( 1 + 0.5)

VpitA / 7100 = 1.3666666

VpitA = 1.3666666 × 7100

VpitA  = 9703.33 ft³

Total cost = volume × unit cost = 9703.33 ft³ × 6 = $58220

Therefore, the total cost to pay Pit A is $58220

3) Calculate the total cost to pay to Pit B = Borrow Pit C: void ratio = 0.81 and the unit cost = $ 4 /ft3

Vpitb / Vcomp = ( 1 + e_{PHB}) / ( 1 + e_{comp )

we substitute

VpitB / 7100 = ( 1 + 0.61) / ( 1 + 0.5)

VpitB / 7100 = 1.0733333

VpitB = 1.0733333 × 7100

VpitB  = 7620.666 ft³

Total cost = volume × unit cost = 7620.666 × 7 = $53344.67

Therefore, the total cost to pay to Pit B is $53344.67

4) Calculate the total cost to pay to Pit C = Borrow Pit D: void ratio = 0.73 and the unit cost = $6 /ft3

VpitC / Vcomp = ( 1 + e_{PHC}) / ( 1 + e_{comp )

we substitute

VpitC / 7100 = ( 1 + 0.81) / ( 1 + 0.5)

VpitC / 7100 = 1.2066666

VpitC = 1.2066666× 7100

VpitC  = 8567.33 ft³

Total cost = volume × unit cost = 8567.33 × 4 = $34269.32

Therefore, the total cost to pay to Pit C is $34269.32

5) Calculate the total cost to pay to Pit D

VpitD / Vcomp = ( 1 + e_{PHD}) / ( 1 + e_{comp )

we substitute

VpitD / 7100 = ( 1 + 0.73) / ( 1 + 0.5)

VpitD / 7100 = 1.1533333

VpitD = 1.1533333 × 7100

VpitD  = 8188.67 ft³

Total cost = volume × unit cost = 8188.67 × 6 = $49132.02

Therefore, the total cost to pay to Pit D is $49132.02

3 0
3 years ago
In the ______ phase of the organizational life cycle, the organization is usually very small and agile, focusing on new products
Vlad [161]

Answer:

Entrepreneurship

Explanation:

Different phases of  organizational life cycles can be observed depending on the stage of the company. These cycles are,

  • Entrepreneurship
  • Survival and Early Success
  • Sustained Success
  • Renewal (or Decline)

In the initial stage which is  Entrepreneurship Phase,  all of the founders take part in various activities, no formality is formed between founders and employees. Generally lots of ideas are present and company is actively searching to define correct market and products to focus on.

5 0
3 years ago
g A smooth pipeline with a diameter of 5 cm carries glycerin at 20 degrees Celsius. The flow rate in the pipe is 0.01 m3/s. What
earnstyle [38]

Answer:

The friction factor is 0.303.

Explanation:

The flow velocity (v), measured in meters per second, is determined by the following expression:

v = \frac{4\cdot \dot V}{\pi \cdot D^{2}} (1)

Where:

\dot V - Flow rate, measured in cubic meters per second.

D - Diameter, measured in meters.

If we know that \dot V = 0.01\,\frac{m^{3}}{s} and D = 0.05\,m, then the flow velocity is:

v = \frac{4\cdot \left(0.01\,\frac{m^{3}}{s} \right)}{\pi\cdot (0.05\,m)^{2}}

v \approx 5.093\,\frac{m}{s}

The density and dinamic viscosity of the glycerin at 20 ºC are \rho = 1260\,\frac{kg}{m^{3}} and \mu = 1.5\,\frac{kg}{m\cdot s}, then the Reynolds number (Re), dimensionless, which is used to define the flow regime of the fluid, is used:

Re = \frac{\rho\cdot v \cdot D}{\mu} (2)

If we know that \rho = 1260\,\frac{kg}{m^{3}}, \mu = 1.519\,\frac{kg}{m\cdot s}, v \approx 5.093\,\frac{m}{s} and D = 0.05\,m, then the Reynolds number is:

Re = \frac{\left(1260\,\frac{kg}{m^{3}} \right)\cdot \left(5.093\,\frac{m}{s} \right)\cdot (0.05\,m)}{1.519 \frac{kg}{m\cdot s} }

Re = 211.230

A pipeline is in turbulent flow when Re > 4000, otherwise it is in laminar flow. Given that flow has a laminar regime, the friction factor (f), dimensionless, is determined by the following expression:

f = \frac{64}{Re}

If we get that  Re = 211.230, then the friction factor is:

f = \frac{64}{211.230}

f = 0.303

The friction factor is 0.303.

4 0
2 years ago
The quantity of bricks required increases with the surface area of the wall, but the thickness of a masonry wall does not affect
Yakvenalex [24]

Answer:

false

Explanation:

5 0
2 years ago
Read 2 more answers
A smooth ceramic sphere (SG 5 2.6) is immersed in a fl ow of water at 208C and 25 cm/s. What is the sphere diameter if it is enc
Aleks [24]

Answer:

a. 4\mu m

b. 1 m

Explanation:

According to the question, the data is as follows

The Density of water at 20 degrees celcius is 1000 kg/m^3

Viscosity is 0.001kg/m/.s

Velocity V = 25 cm/s

V = 0.25 m/s

Now

a. The creeping motion is

As we know that

Reynold Number = (Density of water × V × d) ÷ (Viscosity)

1 = (1,000 × 0.25 × d) ÷ 0.0001

d = (1 × 0.001) ÷ (1,000 × 0.25)

= 4E - 06^m

= 4\mu m

b. Now the sphere diameter is

Reynold Number = (Density of water × V × d) ÷ (Viscosity)

250,000 = (1,000 × 0.25 × d) ÷ 0.0001

d = (250,000 × 0.001) ÷ (1,000 × 0.25)

= 1 m

6 0
3 years ago
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