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trapecia [35]
3 years ago
12

Explain concept of donor levels and accepter levels in extrinsic semiconductors and How can Fermi level be defined for conductor

s , insulators and semiconductors when temperature increases above zero Kelvin.
Physics
1 answer:
nika2105 [10]3 years ago
5 0

Answer:

DONORS: If the material for which it substitutes has more electrons than the original

ACCEPTORS: If the replacement material has fewer electrons than the original material

Fermi level: the point where the probability of finding the last electron is ½

Explanation:

When in a semiconductor material a small fraction of an element is replaced by another with different valences, an excess charge is created.

If the material for which it substitutes has more electrons than the original, there is an excess of electrons, these excess electrons are weakly bound in the material and their orbits are large, in an energy versus moment diagram their energy places them a little more below the conduction band, these materials are called DONORS.

If the replacement material has fewer electrons than the original material, one electron is missing to complete the bonds, so there is a movement of the other electrons, an easier way to analyze this movement of the (n-1) electrons is to suppose that The missing charge has a positive charge and to study its movement, this positive charge is called a hole, its binding energy is small so the orbit of the hole is large, in an energy diagram it is located a little above the band of valence, these are called ACCEPTORS

The Fermi level is defined as the point where the probability of finding the last electron is ½, when the temperature is changed the density of states of the bands changes, therefore the location point moves, but its [probability remains ½

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I was reading an old thermodynamics textbook and came across this equation describing change in internal energy. What does the (
RoseWind [281]

Explanation:

I remember that notation! The expression

dQ = dU = (\dfrac{\partial U}{\partial T})_{V} dT+ (\dfrac{\partial U}{\partial V})_{T}dV

is the 1st law of thermodynamics and it refers to the heat supplied to the system dQ which is also a change in its internal energy dU. The first term is the <u>partial</u> derivative of the internal energy U with respect to temperature T while the volume V is kept constant, as denoted by the subscript V. The 2nd term is similar but this time, temperature is kept constant while its volume partial derivative is being taken.

Ah, memories!

8 0
3 years ago
Alpha particles Ichargeq q = + 2e mass m=6.8*10^ -27 kg) at 17*10^ 4 m/s What magnetic field strength would be required to bend
Rasek [7]

Answer:

Alpha particles Ichargeq q = + 2e mass m=6.8*10^ -27 kg) at 17*10^ 4 m/s What magnetic field strength would be required to bend them into a circular path of radiuse c = 0.25m

Explanation:

Alpha particles Ichargeq q = + 2e mass m=6.8*10^ -27 kg) at 17*10^ 4 m/s What magnetic field strength would be required to bend them into a circular path of radiuse c = 0.25m ok

3 0
4 years ago
Economic growth can be illustrated by: a. ​ an inward shift of the production possibilities curve. b. ​ a movement along the pro
erastovalidia [21]

Answer:

Economic growth can be illustrated by:

d.  an outward shift of the production possibilities curve.

Explanation:

Economic growth is the process of increasing the economy's ability to produce goods and services. It is achieved by increasing the quantity or quality of resources.

Production Possibilities refers to the ability of a country to produce goods or services given the limited resources and technology.  It is therefore possible to increase production of both goods at the same time as long as resources allow it.

The Production Possibilities Curve, also known as the production possibilities frontier, is a graph that shows the maximum number of possible units a company can produce if it only produces two products using all of its resources efficiently. Firstly, and most commonly, growth is defined as an increase in the output that an economy produces over a period of time, the minimum being two consecutive quarters. An increase in an economy's productive potential can be shown by an outward shift in the economy's production possibility frontier (PPF).

Each point on the curve shows how much of each good will be produced when resources shift from making more of one good and less of the other. The curve measures the trade-off between producing one good versus another.PPC or production possibility curve is a curve whose basic purpose is to show the different possible combinations of two goods that can be produced within the given available resource.

The two main characteristics of PPC are: slopes downwards to the right: PPC slopes downwards from left to right. It is because in a situation of fuller utilization of the given resources, production of both the goods cannot be increased simultaneously.

6 0
3 years ago
Assuming that Bernoulli's equation applies, compute the volume of water ΔV that flows across the exit of the pipe in 1.00 s . In
OLEGan [10]

Answer:

discharge rate (Q) = 0.2005 m^{3} / s

Explanation:

if you read the question you would see that some requirements are missing, by using search engines, you can get the complete question as stated below:

Water flows steadily from an open tank as shown in the figure. (Figure 1) The elevation of point 1 is 10.0m , and the elevation of points 2 and 3 is 2.00 m . The cross-sectional area at point 2 is 4.80x10-2m ; at point 3, where the water is discharged, it is 1.60x10-2m. The cross-sectional area of the tank is very large compared with the cross-sectional area of the pipe. Part A Assuming that Bernoulli's equation applies, compute the volume of water DeltaV that flows across the exit of the pipe in 1.00 s . In other words, find the discharge rate \Delta V/Delta t. Express your answer numerically in cubic meters per second.

solution:

time = 1 s

elevation of point 1 (z1) = 10 m

elevation of point 2 (z2) = 2 m

elevation of point 3 (z3) = 2 m

cross section area of point 2 = 4.8 x 10^{2} m

cross section area of point 3 = 1.6 x 10^{2} m

g

acceleration due to gravity (g) = 9.8 m/s^{2}

find the discharge rate at point 3 which is the exit pipe.

discharge rate (Q) = A3 x V3

where A3 is the cross sectional area at point 3 and V3 is the velocity of the fluid and can be gotten by applying Bernoulli's equation below

\frac{P1}{ρg} +  \frac{V1^{2} }{2g} + Z1 =  \frac{P3}{ρg} + \frac{V3^{2} }{2g} + Z3

pressure at point 1 (P1) is the same as pressure at point 3 (P3), and at point 1, the velocity (V1) = 0. therefore the equation now becomes

\frac{P1}{ρg} + Z1 =  \frac{P1}{ρg} + \frac{V3^{2} }{2g} + Z3

Z1 = \frac{V3^{2} }{2g} + Z3

V3 = \sqrt{2g(Z1-Z3)}

V3 = \sqrt{2 x 9.8 x (10 - 3)}

V3 = 12.53 m/s

discharge rate (Q) = A3 x V3 = 1.6 x 10^{-2} x 12.53

discharge rate (Q) = 0.2005 m^{3} / s

8 0
3 years ago
An airplane touches down on the runway with a speed of 70 m/s2. Determine the airplane after each second of its deceleration.
ivann1987 [24]
<span>vf^2 = vi^2 + 2*a*d
---
vf = velocity final
vi = velocity initial
a = acceleration
d = distance
---
since the airplane is decelerating to zero, vf = 0
---
0 = 55*55 + 2*(-2.5)*d
d = (-55*55)/(2*(-2.5))
d = 605 meters


</span>
5 0
3 years ago
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