wu5c12 by Adel Khamis

8/14/2019 wu5c12 by Adel Khamis

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Unit Five -54- Chapter Twelve

Wave Particle Duality

Overview:

Studying physics can be divided into two branches:

Classical physics Quantum (Modern) physics

Explain everything in our

daily life and our common

experiences.

.

.

.

Light:

Light is waves, therefore it .., .,

.. and ...

Visible light is a small part of the electromagnetic waves.

Work Sheet 2007/2008


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Electromagnetic waves propagate in . at speed (3x108

m/sec).

Electromagnetic waves differ in .. and ...

Plancks distribution:

Hot bodies emit and ...

The light emitted from .. consists of all .., but in

different ..

By drawing a graphical relation

between the wavelength and the

radiation intensity, we found that

the radiation intensity ..

by increasing the wavelength then it

.. again.

The wave length at with the

radiation intensity has its maximum

value is decrease by .. the temperature of the source of radiation.

Wiens law:


rays x rays UV Infra redMicrowaves TV

radio

10-12 10-9 10-6 10-3 1 103

Wavelength in meter


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Examples one:

Sun surface temperature is ..K.

The wavelength at the peak is A.

(visible range of light)

40% of the total energy emitted by

sun is in the ..range, 50% is

. (. radiation), while the rest

of energy is distributed over the

remaining spectrum.

Examples two:

Glowing incandescent lamps temperature is .K.

The wavelength at the peak is A.

20% of the total energy emitted by sun is in the range, and most of

the rest of energy is ...

Explanation of Plancks distribution:

Disadvantage of classical physics:

Classical physics cant explain the distribution.

Where the energy is . proportional to the frequency.

Therefore by increase the frequency the radiation intensity will .

Which mean by decrease the wavelength the radiation intensity will .

That can explain the right part of the curve, but not the left part.

Modern physics (Plancks explanation):

Radiation made up of small units (packets) of energy, each called ..

(Photon).



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Electrons rotate in energy levels each has energy = .x.x.

The atom (does / does not) radiate as long as it remains in one energy level.

If the atom shifts from a high energy level to a lower energy level, it emits a

photon whose energy =

Therefore, Photons are (equal / not equal) in energy, but the energy of the

photon is directly proportional to its ..

At small wavelength of radiation (. frequency) the energy of each

photon is (high / low), which lead to (increase / decrease) the number of

emitted photons to keep the energy constant.

The intensity of radiation is indicated by the .. of photons, therefore,

at high frequency the intensity of radiation .., due to the decrease of

photons number and the curve of radiation intensity wavelength becomes

proportional.

Since the total number of photons are so

huge therefore we (can / cant) see

separated photons, but we observe the

features of the stream of photons as a

whole, which represent the classical

properties of radiation

Black body radiation:

All non glowing bodies (even living creatures) (absorb / emit) the radiation

and reemit it.

Bodies of black color absorb (part / all) radiation, therefore it consider as

...



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The black bodies emit the absorbed radiation, therefore it consider as

...

An enclosed cavity with a small hole, canconsidered as black body, because all of the

radiation within the cavity remains trapped

due to .

Small part of the radiation leaks out which

is called ..

Application on Black body radiation:

Earth .. the radiation from the sun, and it.

The temperature of earths surface is (high / low) therefore the wavelength of

emitted radiation at the peak is (low / high) according to .. law.

The peak wavelength is about 10 Micron, which is within the ... region.

Satellites, airborne and terrestrial equipment are mapping the earth surface byusing of all radiation regions including the visible region and the microwave

region in addition to the infrared radiation.

Scientists analyze such images to determine possible .

In military purposes, the same technique is also used as ....

In medicine, it is used to detect ..

In criminology, where the heat radiation from a person lingers for a while even

after the person has left, which called .....



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Photoelectric effect:

Surface potential barrier:

A metal contains (positive /

negative) ions and free electrons

which can move around inside the

metal but cannot leave it, due to

. which known as

..

.. energy or .. energy can overcome the surface potential barrier.

Photoelectric effect:

Definition: ..

Disadvantage of classical physics:

The emission of electrons (the electric current intensity) should be ..

proportional to the intensity of light, but it does not.

The energy of emitted electrons (its

velocity) should be ..

proportional to the light intensity, but it

does not.

In case of low light intensity, giving

sufficient . should give some

electrons enough energy to be freed, but it

does not

The frequency of light (has / has no) effect on the emission of electrons, but it

has.



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Properties of photoelectric effect:

The emission of electrons depends primarily on the .. of the incident

light not on its .

No electrons emit if the frequency of light

(greater / less) than a certain frequencyc, no

matter the intensity of light was.

The emission of electrons occurs instantly as long

as (> / = /


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It does not depend on ..

It does not depend on the .. between the anode and the cathode.

Application on Black body radiation:

Cathode ray tube (CRT):

It consists of tube has narrow end called . (E-gun)

and wide end panted with material called ....

The E-gun contains . and .. connected to (high / low) potential

difference

The cathode is heated by filament heater, to stimulate it to ..

electrons in form of electron beam.

The intensity of electron beam can be controlled by (positive / negative) grid

in its way.

The direction of electron beam can be controlled by or field

in its way to sweep the screen point by point which called ..

When the electron beam fall on the screen it forms an . point, and by

raster the screen images can be formed.

Interpretation of the photoelectric effect:

When the cathode of discharge tube affected by light, it emits ...

By connecting negative potential difference between the anode and cathode,

therefore the velocity of electrons will .., and at a certain potential



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difference (Stopping voltage Vs). The flow of electrons will stop and no

electron arrive to the anode.

At the stopping voltage, the . energy equals to the .. energy ofthe electron

W =

. = KEmax

..............

1Vs =

Sine the electrons emits by the effect of photons energy, therefore:

Photons energy = work function + kinetic energy

.. = . +

KEmax = . -

Which mean that the kinetic energy depends on the of photon,

what ever the intensity of light was.

Example:

By drawing a graphical relation between the stopping potential for different

kind of metals as x-axis, and the kinetic energy of electrons as

y-axis, then:

The mathematical relation: ..

The slope means: ..

By drawing a graphical relation between the square velocity of electrons as

y-axis, and the potential difference of the cathode tube as x-axis, then:

The mathematical relation: .

The slope means: .



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By drawing a graphical relation between the kinetic energy of emitted

electron as y-axis, and the frequency of fallen photon as x-axis, then:


The slope means: .

Intersection with Y-axis means: .

Intersection with X-axis means: .

Compton Effect:

When photon of high frequency (

ray or ..ray) collides with free

electron then:

For photon: frequency .,

and direction .

For electron: velocity , and direction .

This cant explain by classical physics, while the quantum physics can

explain that by using of the conservation law of energy and conservation law of

momentum.

(Energy of photon + Energy of electron) before collision (< / = / >) (Energy of

photon + Energy of electron) after collision.

(Momentum of photon + Momentum of electron) before collision (< / = / >)

(Momentum of photon + Momentum of electron) after collision.

Photon:

Definition: ...

Photon Properties:

According to Planck equation E =



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..

..

..

[0.67 x 10-8 N]

Example:

Calculate the photon mass and linear momentum, if = 380 nm. Given that

Plancks constant = 6.625x10-34 J.sec

..

..

..

..

[5.81 x 10-36 kg, 1.74x10-27 kg m/sec]

N.B:

By drawing a graphical relation between the mass of photon as y-axis, and its

frequency as y-axis, then:


The slope means: ..

By drawing a graphical relation between the mass of photon as y-axis, and

reciprocal of its wavelength as y-axis, then:


The slope means: ..

By drawing a graphical relation between the

momentum of photon as y-axis, and its frequency as y-axis, then:



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The slope means: ..

By drawing a graphical relation between the

momentum of photon as y-axis, and reciprocal of its wavelength as y-axis, then:


The slope means: ..

Application of Einstein equation:

The atomic bomb is an application of Einstein equation where the nuclear

fission is associated with a small (gain/ loss) of mass which is converted to large

amount of energy due to the equation of Einstein:

E = ..

Coincident between microscopic and macroscopic models:

Microscopic model:

Photon can be considered as a sphere of radius ., vibrates with frequency

.

The stream of photons collectively has a .. field and . field.

The two fields are .. to each other and to the direction of

propagation.

The photon stream (flux) carries the of the wave.

The wave intensity measured by measuring the magnitude of .. or

.. field associated with the light wave.

That means that the intensity of wave indicates the . of photons.

N.B.: This model used when deal with very ..objects such as atoms

or electrons.



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Macroscopic model:

The wave motion accompanies the photon stream.

N.B.: This model used when deal with object than the wavelength

of light.

Tomography Scan:

X Rays:

X rays are used to detect tumors, where the body placed on a movable bed,

while the and the . of x rays surrounding the body by .

angles.

By changing the angle of both x rays and the detector together, many images

can be produced.

By using of computer, the images can be collected to produce tomography

picture for the body, which can indicates the ..

MRI:

Magnetic resonance imaging is preferred to x ray in producing tomography

scan, where the x ray has .

A body placed on a movable bed, where a and

.. surrounded it.

The strong magnet used to .. nucleus of hydrogen.

RF used to . the spin motion of the nuclei of hydrogen then the RF

stopped.

The hydrogen nuclei relaxing to their original state, producing .which

can be received by a ., and by using of the computer that can

produce tomography picture for the body, which can detect the ..



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Relation between photon wavelength and its linear momentum:

..........C =

.......

.......=

Multiply the fraction by h (Plancks constant)

.........

.........=

............

h=

Linear momentum (PL) = mc = ................

........

........=

N.B.:

When photons fall on a surface, a comparison is made between the wavelength

and the inter-atomic distance of the surface:

If is greater than the inter-atomic distance, these photons sense the surface as

, and .. from it

If is smaller than the inter-atomic distance, photons .. through the

surface, such as what happens in case of X-Rays.

Wave properties of a particle:

When electron moves with velocity (v), it accompanied with wave, and

wavelength can be determined by using of De-Broglie equation:

.........

........=

The electron wave:

Electron wave is similar to photon wave where both ., ., ..

.. and ...



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Electron wave differ than photon wave, where it is not an .

wave, while it has probabilistic nature.

According to Heisenberg the probability of electron waves denoted by ,

where the location of electron , but the probability 2

indicates its distance from the nucleus.

The probability of being at distance zero from the nucleus is ., or

the electron will..

The probability of being at distance infinity from the nucleus is .,

or the electron will and the atom will

Atom has (greater / lower) energy than its ion by the ionization energy

Electron circulates the nuclei in a path which has number of

wavelength.



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Electron Microscope:

Electron microscope has (lower /

higher) resolving power that

optical microscope.

Electron microscope use

waves, and

lenses.

Due to the wavelength

of electron waves, so it can detect

very small objects.

Quantum Mechanics:

Schrodinger stat the assumptions

of quantum mechanics which used

instead of the classical mechanics if the

object is tightly bounded in a limited size:

Electron energy has a certain value called ., and the atoms (emit /

does not emit) any energy unless it ...

Relaxation: ...

Excitation: ...

Ionization:

Relaxation and excitation are simultaneous processes.

There is a function which is always positive that describes the electron in the

atom.


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wu5c12 by Adel Khamis