Extrinsic Semiconductors

Q.

What is the electron configuration for oxygen?

Q.

In a semiconductor diode, barrier potential offers opposition to only _______.

Q.

What are holes?

Q.

What are the 3 basic elements of communication?

Q.

Take the breakdown voltage of the Zener diode used in the given circuit as $6V$. For the input voltage shown in figure below, the time variation of the output voltage is :

1. 

2. 

3. 

4. 

Q. If a semiconductor has an intrinsic carrier concentration of $\frac{1.41\times {10}^{16}}{m^3}$ when doped with $\frac{{10}^{21}}{m^3}$ phosphorous atoms, then the concentration of holes per cubic meter at room temperature will be

1. $2\times {10}^{21}$
   
2. $2\times {10}^{11}$
   
3. $1.41\times {10}^{10}$
   
4. $1.41\times {10}^{16}$

Q. Find the dispersive power of flint glass. The refractive indices of flint glass for red, yellow and violet lights are $1.613,1.620$ and $1.632$ respectively.

1. $0.0612$
2. $0.310$
3. $0.0306$
4. $0.001$

Q. To obtain p-type extrinsic semi-conductor, the impurity element to be added to germanium should be valency

1. 2
2. 4
3. 5
4. 3

Q.

Which of the following have zero average values in a plane electromagnetic wave?

1. Electric energy

2. Magnetic energy

3. Electric field

4. Both magnetic and electric field

Q.

A P-type semiconductor can be obtained by adding

1. Arsenic to pure silicon

2. Gallium to pure silicon

3. Antimony to pure germanium

4. Phosphorous to pure germanium

Q. Which of the following physical quantities contained in a small volume oscillates at double the frequency of passing electromagnetic wave ? (1 ) Electric field (2 ) Magnetic field (3) Magnetic energy ( 4) All of these (Also give the mathematical reason)

Q.

Silicon is a semiconductor. If a small amount of As is added to it, then its electrical conductivity

1. Increases

2. Decreases

3. Remains unchanged

4. Becomes zero

Q. What is the number density of donor atoms which must be added to a pure germanium semiconductor to produce an N-type semiconductor of conductivity $6.4\times {10}^2{\text{ohm}}^{–1}{\text{m}}^{–1}$ ? The mobility of electrons in N-type germanium is $4\times {10}^{–1}{\text{m}}^2{\text{V}}^{–1}{\text{s}}^{–1}$. Neglect contribution of holes to conductivity.

1. ${10}^{20}{\text{m}}^{-3}$
2. ${10}^{21}{\text{m}}^{-3}$
3. ${10}^{22}{\text{m}}^{-3}$
4. ${10}^{23}{\text{m}}^{-3}$

Q. The bipolar junction transistor is used as a switch ‘ON’ in

1. Active region
2. Cut off region
3. Saturation region
4. Both $\left(B\right)$ and $\left(C\right)$

Q.

The valence of an impurity added to germanium crystal in order to convert it into a P-type semi conductor is ?

1. 6

2. 5

3. 4

4. 3

Q.

Which side of a PN junction should be connected to the positive voltage for forward bias?

Q. In a bipolar junction transistor (BJT)

1. The base has the least concentration of impurity
2. The emitter has least concentration of impurity
3. All the three regions have equal concentration of impurity
4. The collector has least concentration of impurity

Q. If $N_P$ and $N_e$ be the numbers of holes and conduction electrons in an extrinsic semiconductor, then

1. N_P > N_e
2. N_P = N_e
3. N_P < N_e
4. N_P > N_e or N_P < N_e depending on the nature of impurity

Q. the electric field part of an emw in vacuum is given by E=6cos (1.2y +3.6 810^8 t) i cap , then find 1.direction of propagation 2.expression for magnetic field part of the wave . HOW TO FIND DIRECTION OF MAGNETIC FIELD ?

Q.

Q. what is the order of energy gap in metal , semiconductor and insulator.

Q. In a semiconductor, the concentrations of electrons and holes are $8\times {10}^{18}/m^3$ and $5\times {10}^{18}/m^3$ respectively. If the mobilities of electrons and hole are $2.3m^2$/volt-sec and $0.01m^2$/volt-sec respectively, then semiconductor is:

1. N-type and its resistivity is 0.34 ohm-metre
2. N-type and its resistivity is 0.034 ohm-metre
3. P-type and its resistivity is 3.40 ohm-metre
4. P-type and its resistivity is 0. 134 ohm-metre

Q. masses of three wire of copper are in the ratio of 135 and their length are in the ratio 531 and its ratio of their electrical resistance is

Q. what is phase difference between electic and magnetic field of electromagnetic waves

Q.

A body P contains $50$ electrons and $45$ protons and a body Q contains $72$ electrons and $77$ protons after electrification by friction between the bodies. Find the number of electrons and protons in P and Q before electrification. Also find the number of electrons transferred between them.

Q.

What is the most commonly used semiconductor material?

Q. The magnetic field in a travelling electromagnetic Wave has a peak value of 20 not. The peak value of electric field strength is

Q.

Which of the statements given in Exercise 14.1 is true for p-type semiconductors.

Q. What is biasing a diode? Write two differences between the two kinds of biasing.

Q.

What is forward and reverse bias?