chapter 14 class 12 physics notes

chapter 14 class 12 physics notes:-

SEMICONDUCTOR ELECTRONICS :-

 

semiconductor is the fundamental basis of electronics ,if we referring electronics we must know about semiconductor first ,in our previous post we already discuss about basis of semiconductor if you want to revise this topic you can search in our site ,here we provide you notes PDF fro "chapter 14 class 12 physics notes"

 

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• Continue reading with:
• Guass theorem
• Photoelectric effect
• Compton effect
• Semiconductor
• Electrostatics (physics class 12)
• transformer
• Solid state (chemistry class 12)
• Electromagnetic induction

 

Guass theorem class 12

class 12 physics

Guass theorem class 12:---

class 12 is very important turning point in a student life , so to perform best in your most important class is become a matter of distress ,to relieve your stress to some extent.we providing you Guass theorem and various other topic relates to class 12 physics in PDF .these are handwritten which help you better understanding of these topic.i hope you like it if you have any query related to this topic write us on comment box 

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 Continue reading with:

• Photoelectric effect
• Compton effect
• Semiconductor
• Electrostatics (physics class 12)
• transformer
• Solid state (chemistry class 12)
• Electromagnetic induction

class12| chemistry notes|chapter 1|PDF

CLASS 12 CHEMISTRY NOTES UNIT 1 PDF:

 

class 12 is significant defining moment in an student life , so to perform best in your most significant class is turned into a matter of misery ,to mitigate your worry to some extent.we giving you science notes to class 12 part 1 PDF .these are written by hand which help you better comprehension of these topic.i trust you like it on the off chance that you have any inquiry identified with this point keep in touch with us on remark box
 CBSE Class 12 Chemistry Notes in PDF to enable  to comprehend that Chemistry is tied in with learning substance components  and how these things cooperate to shape various chemical conditions.

To score high  in science especially in chemistry,  need to remember the compound equations by heart. One method for doing as such is experiencing and understanding the science notes for class 12 completely. These equations would not just assist the student with achieving a high score in school tests, yet additionally in CBSE Class 12 Chemistry Board Exam and much more.

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photoelectric effect

Photoelectric effect:-

according to quantum theory of light,

When electromagnetic waves propagate it carries energy in packet or pieces ( it means that energy is quantized )

Electromagnetic energy carries in packet or pieces according to quantum theory of light given by Einstein.

This packet of energy called photon and the energy of photon is given by

  E = hf, 

where h is Planck's constant and f is the frequency.

ACCORDING TO ABOVE RELATION, amount of energy related to frequency of that wave.

If we increase frequency we increase amount of energy (of photon).

What quantum mechanics tell us about subatomic particle?

especially electron.

Electromagnetic waves carry amount of energy In the same way , electron also carry some amount of energy.

As we study in chemistry, normally electron remain in ground state (lowest level of energy) when some amount of energy given to electron and it able to overcome coulomb force of attraction between electron and proton .

then electron gets excited move in excited state but remain there temporary it soon releases energy and return back to its ground state it releases energy in the form of light.

Same phenomenon used by Einstein to give photoelectric effect,

We all know about electrostatics force, proton in nucleus pull electron with a coulomb force,in order to free electron we have to provide more energy than that coulomb force.

Einstein conducted a experiment,

,he took a electron, He said that ,I shine light on my electron and that light have low energy that not high enough to excite a electron 

Then he increase intensity of that light and find that electron was not excited even now, then he said if light travels like a wave (according to it energy of light proportional to it intensity  i.e, more the intense of light ,more energy it carries.)

If there is increase in energy, by increasing intensity my electron must get excited. but that was not happen here.

Now, from quantum theory of light, we know that light carries energy in the form of packet known as quanta energy it carries is given as ,

  E = hf, 

where h is Planck's constant and f is the frequency.

From above equation we know that energy directly proportional to frequency. what happens if we increase frequency of light in above experiment . 

Einstein reconduct the experiment and find that on increasing the frequency electron gets excited .

IT MEANS THAT LIGHT TRAVEL IN THE FORM OF PARTICLE

Photoelectric effect gives experimental prove to quantum theory of light.

 now, question arises what is photoelectric effect?

The photoelectric effect s the emission of electrons from the surface of matter generally, a metal in response to the incident light. 

but in a condition that frequency of incident light must be greater than threshold frequency (it is a minimum frequency require to electron gets excited or gets free ).

Energy contained within the incident light is absorbed by electrons within the metal, giving the electrons sufficient energy to be knocked out or get free of the surface of the metal.

Continue reading with:

• Guass theorem
• Photoelectric effect
• Compton effect
• Semiconductor
• Electrostatics (physics class 12)
• transformer
• Solid state (chemistry class 12)
• Electromagnetic induction

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ELECTROMAGNETIC INDUCTION

 ELECTROMAGNETIC INDUCTION

Magnetic Flux :

Magnetic Flux through any surface is the number of magnetic lines of force passing normally through that surface.




mathematically,

magnetic flux given by dot product of strength of magnetic field B and area of surface ds. 
dΦ = B . ds

dΦ = B . ds cos θ

for a coil ,

Φ = B . A
 

Φ = B . A cos θ

 SI unit of magnetic flux is weber or tesla-metre2 or ( wb or Tm2) and cgs unit of magnetic flux is maxwell. (1 maxwell = 10-8 weber).

 Magnetic flux is a scalar quantity.

 Magnetic Flux across a coil can be changed by changing following quantities:

1)By  the strength of the magnetic field B.
2) By the area of cross section of the coil A or area of surface .
3)By the orientation of the coil with magnetic field (cos θ).

 Faraday’s Laws of Electromagnetic Induction:

 Faraday’s I Law:
Whenever there is a change in the magnetic flux linked with a circuit, an induced emf is produced and as a result  current is induced in the circuit. However, it lasts untill magnetic flux is changing.
 Faraday’s II Law:
The magnitude of the induced emf is directly proportional to the rate of change of magnetic flux linked with a circuit.
E α dΦ / dt
E = k dΦ / dt
(where k is a constant and units are chosen such that k = 1)
E = dΦ / dt
or
 E = (Φ2 – Φ1) / t

Compton Effect

Compton Effect:

·          








      

       


        
       
     

        Photoelectric effect proved quantum theory of light at basic level.

·         It confirmed that light consist of individual photon that carry energy, depends upon frequency of oscillation of light.

·         Another experiment that proved quantum theory of light was Compton effect

·         In Compton effect, Compton makes electromagnetic waves with shorter wavelength (x rays) to fall at stationary electron,

·         he examined collision between the electromagnetic waves and electron,

·         he found that reflected electromagnetic wave has greater wavelength than the wave incident on electron on collision.

·         “Wavelength of the scattered X rays was larger than incident X rays in collision of X rays and a stationary electron, this effect is known as Compton effect”

·         Using conservation of energy and momentum, he was able to derive the following equation,

·         Compton shift =shift in wavelength

·         This is known as Compton shift

·         Now question arises how Compton Effect proves quantum theory of light?

·         According to wave theory there is no change take place in wavelength in any collision.

·         The incident electromagnetic wave cause electron to oscillate with same frequency as that of incident waves when the electron reemitted the waves its must be of same frequency as that of incident waves so there is no shift in frequency which implies there is no shift in wavelength according to wave theory

·         But this is not happen in actual experiment conducted by Compton, in Compton experiment there is a shift in Wavelength.

·         It proves that wave theory is not applicable here, from quantum theory of light ,lets examined Compton experiment through quantum theory of light and found that  it is applicable or not

·         Lets photon collides with that stationary electron and in this collision some of energy within photon goes into the electron, (similarly the case of particles collision in which transfer of energy take place).

·         Now, electron gain kinetic energy and begin to move with same velocity and scattered photon has less energy than before.

·         Energy depends on frequency, less energy means less frequency and smaller frequency means greater wavelength as frequency is inversely proportional to wavelength.

·         So that scattered waves has larger wavelength and therefore quantum theory of light is successfully describe Compton experiment related to Compton effect  and its contrary is also true.

    Continue reading with:

•     Guass theorem
•     Photoelectric effect
•     Compton effect
•     Semiconductor
•     Electrostatics (physics class 12)
•      transformer
•     Solid state (chemistry class 12)
•     Electromagnetic induction

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magnetic effect of current

MAGNETIC EFFECT OF CURRENT

·       Magnetic Effect of Current

·       Right Hand Thumb Rule

·       Maxwell’s Cork Screw Rule

·       Biot –Savart’s Law

Right Hand Thumb Rule:

If a current carrying conductor is to be hold in the right hand then the thumb points in the direction of the current, and tips of the fingers encircling the conductor will give the direction of the magnetic lines of force.

Maxwell’s Cork Screw Rule:

If motion of an imaginary right handed screw is in the direction of the current through a linear conductor, the direction of rotation of the screw gives the direction of the

magnetic lines of force around the conductor.

Biot – Savart’s Law:

The strength of magnetic field dB due to a small current carrying element dl carries a current I at a point P distant r from current element is directly proportional to I (length of the wire), dl(value of small element length at which magnetic field is calculated), sin θ and inverselyproportional to the square of the distance (r2) where θ is the angle between dl and r.

small magnetic field at dl is given by

dB α I

 dB α dl

 dB α sin θ

 dB α 1 / r2

dB αI dl sin θ/r2

dB =μ0  / 4π ( I dl sin θ /r2 )

Value of μ0 = 4π x 10-7 Tm A-1 .

Continue reading with:

• Guass theorem
• Photoelectric effect
• Compton effect
• Semiconductor
• Electrostatics (physics class 12)
• transformer
• Solid state (chemistry class 12)
• Electromagnetic induction

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