What's energy band theory???

Answers

Answer 1

Answer:

Energy band theory is a basis for describing processes and effects in solid crystals under electromagnetic field impact.

Explanation:

Single atoms have a discrete energy spectrum, which means they can occupy only discrete energy levels. Part of these energy levels are filled with electrons in a non-excited condition. Part of these levels can be occupied only when electrons are excited.


Related Questions


A particular electric car is supplied with 300 kJ of chemical energy by the battery. Of this, a total of 70.5 kJ of energy is wasted as heat.
Calculate the overall efficiency of the electric car.

Answers

Supplied energy=300kJ

Wasted energy=70.5J

Used energy:-

[tex]\\ \sf\longmapsto 300-70.5=229.5kJ[/tex]

We know

[tex]\boxed{\sf Efficiency=\dfrac{Used\:Energy}{Supplied\:Energy}\times 100}[/tex]

[tex]\\ \sf\longmapsto Efficiency=\dfrac{229.5}{300}\times 100[/tex]

[tex]\\ \sf\longmapsto Efficiency=\dfrac{229.5}{3}[/tex]

[tex]\\ \sf\longmapsto Efficiency=76.5\%[/tex]

The overall efficiency of the electric car = 76.5 %

To find the efficiency the given values are:

Energy supplied = 300 kJ

Energy wasted = 70.5 kJ

Define efficiency and calculate the value of efficiency.

      In the system the output energy is compared to the input energy is known as efficiency. That can be written as percentage ratio of output energy to the input energy.

Formula of efficiency is,

             Efficiency = ( E out / E in ) × 100

Here, Energy supplied = 300 kJ

so, energy used = Energy supplied - Energy wasted

                           = 300 - 70.5

                           =  229.5 kJ

Thus, substituting E out = 300 kJ , E in = 229.5 kJ

            Efficiency = ( 229.5 / 300 ) ×100

                             = 229.5 / 3

                             = 76.5

Hence, The overall efficiency of the electric car is 76.5 %

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numerical filing method is more scientific why give me 4 reason ​

Answers

Answer:

Numerical Methods are mathematical way to solve certain problems.Whether the equations are linear or nonlinear, efficient and robust numerical methods are required to solve the system of algebraic equations.

Analytical solutions are exact solutions based on mathematical principles.

However, the governing partial differential equations of fluid flow are complex and cannot be solved by analytical means. The partial differential equations are therefore converted into a system of algebraic equations that are subsequently solved through numerical methods to provide approximate solutions to the governing equations.

Although we rarely reach on exact answer , we can get really close to the exact answer much quicker than solve analytically.

Answer:

oh my god

Explanation:

how long answer is this

State any ten reasons why students in Uganda need to study physics?use examples of the possible technological advancements which can be made using the knowledge of physics

Answers

Answer:

1.it also hleps us to became doctors becuase without physics you can't be a doctor

2.physics needs to be steady whether you like it or not it helps you in life so everybody must study physics no matter is in Uganda USA and plenty more countries there must be physics to dare to be studied

Which is an outer planet?

Answers

Answer:

pluto

Explanation:

Dwarf because it is very minut

Answer:

I think Saturn.

Explanation:

I think the inner planets are Mercury, Venus, Earth and Mars whereas the outer ones are Jupiter, Saturn, Uranus and Neptune.

Why do scientists not use US customary units when reporting their data?

Answers

from britaññica it said time and money. They didn’t have either to switch over from the industrial period and never did. Also from my own person reasoning i think most of the world uses not US customary, so to make stuff more accessible. hope this helps!

Why do scientists not use US customary units when reporting their data?

Answers

One of the scientist's jobs is to report the results of his experiments to all the other scientists in the world.

There isn't a single real science shop anywhere in the world that uses the US customary system of units. Not one.

Even in the measly three countries that use it for measuring carpet, pumping gas, and weighing fish ... Myanmar, Liberia, an the USA ... the scientists do their work in the SI/MKS/metric system.

A hockey puck has a mass of 0.21 kg. If the hockey puck
is moving with 74 J of kinetic energy, what is its speed?
Show all your work.

Answers

Answer:

v = 26.54 m/s

Explanation:

Given that,

The mass of a hockey puck, m = 0.21 kg

The kinetic energy of the hockey puck, E= 74 J

We need to find the speed of the hockey puck. Let the speed is v. We know that, the kinetic energy is given by :

[tex]E=\dfrac{1}{2}mv^2[/tex]

Where

v is the speed

So,

[tex]v=\sqrt{\dfrac{2E}{m}} \\\\v=\sqrt{\dfrac{2\times 74}{0.21}} \\\\v=26.54\ m/s[/tex]

So, the speed of the hockey puck is 26.54 m/s.

6.
For a given prism the angle of incidence is changed from 0° and 90', the angle of deviation [ ]
b) decreases
c) first decreases and then increases
d) first increases and then decreases
a) increases

Answers

Answer:

increase

Explanation:

please mark as brainlyest

Answer

A.Increses

Explanation:

Tính công của dòng điện

Answers

Answer:

CG gh sure er go b vh pxuh FPI OO c AM h kh

A sound frequency 100Hz and wavelength 3.34m is travelling through air, calculate the Velocity of sound in air.

Answers

Answer:

334m/s

Explanation:

If you take the data you gave and insert it into the equation f=v/λ the frequency would come out to be 3.34m

334 m/s is  the Velocity of sound in air.

What is the velocity of a wave?

Wave velocity in common usage refers to speed, although, properly, velocity implies both speed and direction.

The velocity of a wave is equal to the product of its wavelength and frequency (number of vibrations per second) and is independent of its intensity.

Mathematically , v=fλ

According to the question,

Sound frequency (f)  = 100Hz

Wavelength (λ)= 3.34m

Computing the values in the formula,

v=fλ

v = 100Hz x 3.34m

v= 334m/s

Therefore,

Velocity of sound in air is 334 m/s.

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Calculate the upthrust on a object immersed in water if the object displace water of mass 2 kg.(g=9.8m/s²) ​

Answers

Thrust is force

Mass=2kgAcceleration due to gravity=g=9.8m/s^2

Using Newtons Second law

[tex]\boxed{\sf Force=Mass\times Acceleration}[/tex]

[tex]\\ \qquad\quad\sf{:}\dashrightarrow Thrust=2(9.8)[/tex]

[tex]\\ \qquad\quad\sf{:}\dashrightarrow Thrust=19.6N[/tex]

We have that the the upthrust on a object immersed in water is

[tex]U=19.6N[/tex]

From the Question we are told that

mass= 2kg

Gravity g=9.8m/s^2

Generally the equation for the upthrust  is mathematically given as

[tex]U=mg[/tex]

Therefore

[tex]U=2*9.8[/tex]

[tex]U=19.6N[/tex]

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Help me frfr I don’t understand

Answers

The points are

(1,10)

(6,0)

[tex]\boxed{\sf slope(m)=\dfrac{y_2-y_1}{x_2-x_1}}[/tex]

[tex]\\ \sf\longmapsto m=\dfrac{0-10}{6-1}[/tex]

[tex]\\ \sf\longmapsto m=\dfrac{-10}{5}[/tex]

[tex]\\ \sf\longmapsto m=-2[/tex]

A train 90m long stops in a train station with its front buffers in line with a lamp post on the platform. Later it starts off with an average acceleration of 0.45m/s. What will be its speed in kilometers per hour when the tail buffers pass the lamp post P?​

Answers

Answer:

The speed of the train when the tail buffers pass the lamp post is 9 m/s

Explanation:

The given parameters are;

The length of the train = 90 m

The initial velocity of the train, u = 0

The average acceleration of the train, a = 0.45 m/s²

When the tail buffer pass the lamp post, P, we have;

The distance travelled, s = The length of the train = 90 m

The kinematic equation of motion is given as follows;

v² = u² + 2·a·s

Where;

v = The speed of the train when the tail buffers pass the lamp post

∴ v² = 0² + 2 × 0.45 m/s² × 90 m = 81 m²/s²

Therefore;

v = √(81 m²/s²) = 9 m/s

The speed of the train when the tail buffers pass the lamp post, v = 9 m/s.

on
when you throw a ball
the
ground
and it
bounces back to your hand,
is it elastic collision ? Explain.

Answers

Answer:

The ground hits the ball with same force with which the balls hit the ground. That's why ball bounces back.

Gravity stops it from bouncing forever.

Hope this helps..

An object of mass 10 kg has a momentum of 15 kg m/s. Find the average force required to accelerate the object to 10 m/s over 20 seconds.

Answers

Answer:

Force = 4.25 Newton

Explanation:

Given the following data;

Mass = 10 kg

Momentum = 15 Kgm/s

Time, t = 20 seconds

Final velocity, V = 10 m/s

To find the average force required;

First of all, we would determine the initial velocity of the object.

Momentum = mass * velocity

15 = 10 * velocity

Velocity = 15/10

Velocity = 1.5 m/s

Next, we would determine the acceleration of the object by using the first equation of motion;

V = U + at

10 = 1.5 + a*20

10 - 1.5 = 20a

8.5 = 20a

Acceleration, a = 8.5/20

Acceleration, a = 0.425 m/s²

Lastly, we would find the average force by using the formula;

Force = mass * acceleration

Force = 10 * 0.425

Force = 4.25 Newton

Define measurement with examples.​

Answers

Explanation:

Measurement is defined as the act of measuring or the size of something. An example of measurement means the use of a ruler to determine the length of a piece of paper. An example of measurement is 15" by 25". ... The dimension, quantity, or capacity determined by measuring.

Measurement refers to the comparison of unknown physical quantity with a known quantity.

for eg. measurement of body while sewing clothes.......

Two rams run toward each other. One ram has a mass of 44 kg and runs south with a speed of 6 m/s, while the other has a mass of 50 kg and runs north with a speed of 3 m/s. What will the momentum of the system made up of the two rams be after they collide? Assume the total momentum of the system is conserved.
A. 114 kg-m/s south
B. 414 kg-m/s south
C. 414 kg m/s north
D. 114 kg-m/s north

Answers

Answer = D. 114 kg-m/s north

what is momentum
what is momentum in words​

Answers

Answer:

It's a strength or force

Explanation:

the quantity of motion of a moving body, measured as a product of its mass and velocity

Answer:

momentum is a quality define as the product of the mass and velocity of an object.

cho 11,2 lit hỗn hợp gồm metan và etilen tác dụng với dung dịch brom. sau phản ứng xảy ra toàn thấy có chất khí thoát ra và 40 gam brom tham gia phản ứng .
a) viết phương trình phản ứng xảy ra
b) tính thành phần phần trăm thể tích mỗi chất trong hỗn hợp
c) đốt cháy toàn bộ thể tích khí thoát ra sau đó cho chất khí thu được tác dụng với 100ml dung dịch Ca(OH)2 1,25 M. tính khối lượng chất thu được sau phản ứng . biết metan ko tác dụng với brom , các chất khí đo ở điều kiện tiêu chuẩn

Answers

Yes he was the strongest hahaha

Which type of reactions usually happens slowest?

Answers

Answer:

option b is correct..................

A ferrari has a mass of 1485kg.what is it's weight on Earth ​

Answers

F = m · g

m = 1485 kg

g = 10 N/kg

F = 1485 kg · 10 N/kg = 14 850 N = 14,85 kN

Answer: The weight on Earth is 14,85 kN.

An object moving north with an initial velocity of 14 m/s accelerates 5 m/s2 for 20 seconds. What is the final velocity of the object?
39 m/s
90 m/s
114 m/s
414 m/s

Answers

Answer:

option C

Explanation:

Final velocity of the object is 114 m / s. Hence, final velocity of the object is 114 m / s.

Here is the answer ! Hope it helps.

calculate the potential energy stored in a meta ball of mass of 80 kg kept at a height of 15m from the earth surface . What will be the potential energy when the metal ball is kept on the earth surface Take (g- 9.8 m/s] ​

Answers

Answer:

11760 J

Explanation:

cuz potential engery is PE = MHG

SO 80×15×9.8= 11760 J

Answer:

11769j

Explanation:

here,

mass(m)=80 kg

height(h)=15m

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

now,

potential energy = m×g×h

= 80×9.8×15

= 11760j

20. A semiconductor is a
crystalline solid that conducts current under any condition
metallic solid that conducts current under any condition
metallic solid that conducts current under certain conditions
crystalline solid that conducts current under certain conditions

Answers

Answer:

D. crystalline solid that conducts current under certain conditions

Explanation:

Semiconductors are crystalline solids that has the ability to conduct electrical currents but on certain conditions e.g heat. The conduction of semiconductors is less than that of conductors (metals) but more than insulators (nonmetals), hence, they are said to be intermediates of conductors and insulators in terms of electrical conductivity.

Examples of semiconductors are silicon, boron, carbon, germanium, arsenic etc.

help with this physics question please :)

Answers

Answer:

is that rm in you profile pic

Why is it difficult to maintain constant speed of a vehicle?​

Answers

Answer:

The road surface is always rough, so the frictional force between the tires and the road surface make it difficult to maintain constant speed because acceleration always changes.

Hey there!

Yes, it's difficult to maintain a constant speed of a vehicle.

Explanation:

Because, roads surfaces are not always smooth, they are rough too, for which friction occurs.

Hope it help you

A cricketer throws a ball sideways with an initial velocity of 30 m/s. She releases the ball from a height of 1.3m. Calculate how far the ball travels before hitting the ground.

Answers

Answer:

78.34

Explanation:

1.3/30=78.3m

Please help have due very soon?thank you

Answers

The answer is :78 I think

Write down the role played by four digestive juices in digestion and the
organs which secrete them.

Answers

Answer:

Digestive juices secreted by various organs such as salivary glands in the mouth, stomach, liver and pancreas help in the process of digestion of food. Saliva secreted by the salivary glands in the mouth aids in the breakdown of starch present in the food to simple sugar

Explanation:

state any two effects of gravitational force ​

Answers

Answer:

The effect of gravity extends from each object out into space in all directions, and for an infinite distance. However, the strength of the gravitational force reduces quickly with distance. Humans are never aware of the Sun's gravity pulling them because the pull is so small at the distance between the Earth and Sun.

Answer:

The Earth's gravitational force accelerates objects when they fall. It constantly pulls, and the objects constantly speed up.

Explanation:

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