Wave Worksheets Notes By- PRATAP KUMAR

 Wave Worksheets 

Which is very helpful for quick revision of main basic fundamentals concepts of Physics.

To determine the Energy Band Gap of a Semiconductor by using PN Junction Diode.

Aim: To determine the Energy Band Gap of a Semiconductor by using PN Junction Diode. Apparatus: Energy band gap kit containing a PN junction diode placed inside the temperature controlled electric oven, microammeter, voltmeter and connections brought out at the socket, a mercury thermometer to mount on the front panel to measure the temperature of oven. Formula Used: The reverse saturation current, Is is the function of temperature (T) of the junction diode. For a small range of temperatures, the relation is expressed as, 

Where, T is temperature in Kelvin (K) and Eg is the band gap in electron volts (eV). Graph between 103/T as abscissa and log10 Is as ordinate will be a straight line having slope = 5.036 Eg Hence band gap, 

Theory: A semi-conductor (either doped or intrinsic) always possesses an energy gap between its valence and conduction bands (fig.1). For the conduction of electricity, a certain amount of energy is to be given to the electron so that it can jump from the valence band to the conduction band. The energy so needed is the measure of the energy gap (Eg) between the top and bottom of valence and conduction bands respectively. In case of insulators, the value of Eg varies from 3 to 7 eV. However, for semiconductors, it is quite small. For example, in case of germanium, Eg = 0.72 eV and in case of silicon, Eg = 1.1 eV.  

In semi-conductors at low temperatures, there are few charge carriers to move, so conductivity is quite low. However, with increase in temperature, more number of charge carriers get sufficient energy to be excited to the conduction band. This lead to increase in the number of free charge carriers and hence increase in conductivity. In addition to the dependence of the electrical conductivity on the number of free charges, it also depends on their mobility. The mobility of the charge carriers, however decreases with increasing temperature. But on the average, the conductivity of the semiconductors rises with rise in temperature. To determine the energy band gap of a semi-conducting material, we study the variation of its conductance with temperature. In reverse bias, the current flowing through the PN junction is quite small and internal heating of the junction does not take place. When PN junction is placed in reverse bias as shown in fig.2(a), the current flows through the junction due to minority charge carriers only. The concentration of these charge carriers depend on band gap Eg. The saturation value, Is of reverse current depends on the temperature of junction diode and it is given by the following equation,

Precautions: The following precautions should be taken while performing the experiment: 1. The diode must be reverse biased. 2. Do not exceed the temperature of the oven above 100℃ to avoid over heating of the diode. 3. The voltmeter and ammeter reading should initially be at zero mark. 4. Bulb of the thermometer should be inserted well in the oven. 5. Readings of microammeter should be taken when the temperature is decreasing. 6. Readings of current and temperature must be taken simultaneously. Sample viva voce questions: 1. What is PN junction diode? 2. What do you understand by band gap of a semi-conductor? 3. What do you mean by valence band, conduction band and forbidden band? 4. How many types of semi-conductors are there? 5. What are P-type and N-type semi-conductors? 6. Define doping and dopant. 7. Why P-type (N-type) semi-conductor is called Acceptor (Donor)? 8. What do you mean by Fermi energy level? 9. What is the position of Fermi level in an intrinsic semi-conductor and in a p-type or n-type semi-conductor with respect to the positions of valence and conduction bands? 10. What do you mean by forward biasing and reverse biasing? 11. Why diode is reverse biased in determining the band gap of semi-conductor? 12. What is the shape of graph between log10 Is and 103/ T? How do you find band gap energy from this graph? 13. Why conductivity of metals decreases with increase in temperature? 14. Why conductivity of a semi-conductor increases with increase in temperature? References:  Solid State Electronic Devices by Streetman and Banerjee  B.sc Practical Physics by Geeta Sanon 

 

Central University Common Entrance Test (CUCET) 2020 Questions Paper and Answer Key

 Central University Common Entrance Test (CUCET) 2020 is a best option for those students who want to take addmission in reputated colleges and universities. In this examination you have more option for take admission in huge amount of various courses. 

Some students want to take addmission on own choice so this examination is the better opportunity for the students. 

Some course are given below:-

(1) M.Sc. Physics

(2) M.Sc. Statistics

(3) M.Sc. Mathematics

(4)  M.Sc. NanoScience And Technology

(5) M.Sc. Bio - technology &

(6) M.Sc. Chemistry etc.

Answer key of questions paper:-

Test Paper Code	Answer key
PGQP26	Click Here
PGQP28	Click Here
PGQP32	Click Here
PGQP54	Click Here
PGQP55	Click Here

Final Answer Key

Test Paper Code	Final Answer key
PGQP26	Click Here
PGQP28	Click Here
PGQP32	Click Here
PGQP54	Click Here
PGQP55	Click Here

(1) M.Sc. Physics Questions Paper are given below:-

Add caption

Fee Structure of different courses are given below:-

Class 12th, IIT JEE and Other Entrance Examination Topics wise Notes

Class 12 Physics Notes – Free PDF Download Chapter wise

1. Electric Charges and Fields
2. Electrostatic Potential and Capacitance
3. Current Electricity
4. Moving Charges and Magnetism
5. Magnetism And Matter
6. Electromagnetic Induction
7. Alternating Current
8. Electromagnetic Waves
9. Ray Optics and Optical Instruments
10. Wave Optics
11. Dual Nature of Radiation and Matter
12. Atoms
13. Nuclei
14. Semiconductor Electronic: Material, Devices And Simple Circuits
15. Communication Systems

LIST OF PHYSICS TOPICS	DOWNLOAD LINK
ELECTROSTATICS	DOWNLOAD
CURRENT ELECTRICITY	DOWNLOAD
MAGNETIC EFFECT OF CURRENT AND MAGNETISM	DOWNLOAD
ELECTROMAGNETIC INDUCTION AND AC	DOWNLOAD
ELECTROMAGNETIC WAVES	DOWNLOAD
OPTICS	DOWNLOAD
DUAL NATURE OF MATTER AND ENERGY	DOWNLOAD
ATOMS AND NUCLEI	DOWNLOAD
ELECTRONIC DEVICES	DOWNLOAD
COMMUNICATION	DOWNLOAD

The Best Hand Written Notes For Class 11 & 12 Physics Students

The Best Hand Written Notes For B.Sc. Physics Students

You Can Visit On My Youtube Channel  Click Here For Notes.

1. Electronic Hand Written Notes 

Link - Download PDF File

2. Solid State Physics Hand Written Notes 

Link - Download PDF File

3. Mathematical Physics Hand Written Notes
Link - Download PDF File

4.Neculear Physics Hand Written Notes
Link - Download PDF File

5. Partical Physics Hand Written Notes
Link - Download PDF File

6. Quantum Physics Hand Written Notes
Link - Download PDF File

7. Statistical Physics Hand Written Notes
Link - Download PDF File

8. Thermodynamics Hand Written Notes
Link - Download PDF File

For More Hand Written Notes PDF File You Can Add On My 
Google Classroom Class Code - c3mmopy

Physics Notes

Physics Notes

1. Amplitude Modulation Notes :-https://engineerstutor.com/2018/10/03/am-amplitude-modulation-mathematical-derivation/

I. The Rutherford Model OF The Atom

The first exploration of the structure of the atom was made by Rutherford in 1911 making use of α-particles. He bombarded a thin gold foil with  α-particles (helium nuclei, which are positively charged particles with an atomic mass number of 4) and found that very many  α-particles passed through the gold foil without being deflected, but some of them were deflected through a large angle. The inference was that much of the atom has void space between them, allowing most of the  α-particles to pass straight through, but with some particles being deflected owing to their passing close to, or colliding with, a central mass (nucleus) or very small dimensions. The effective diameter of the gold atom is 0.3 nm and the diameter of the nucleus is about 1/10,000 of this size. The first postulation about electrons was that they are in orbit around the central nucleus just as planets round the sun. To  incorporate these findings and the discovery of the electron, Rutherford proposed the following model of the atom: This model postulates a tiny, massive and positively charged nucleus around which the negative electrons orbit. In Fig. 2.1, an electron is revolving in a circular orbit of radius,  r, with a constant velocity,  v. The system is now subjected to two forces. Acting inwards will be electrostatic attraction given by Coulomb’s law 

 Here  ε0  is the  permittivity of free space. The other one is the  centrifugal force,  fc  acting outwards. The value of this force is 

where  m  is the mass of the electron and (v2/r) is its  radial acceleration. The condition for orbit stability is fc = fe.

Thus,