What is valence band and conduction band

EASY

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

Draw separate energy band diagrams for conductors, semi-conductors and insulators and label each of them.

EASY

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

If the forbidden energy gap in a substance is

1 eV

, substance is a

EASY

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

State anyone difference between the energy band diagram of conductors and that of insulators.

EASY

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

The Forbidden gap between conduction band & valance band is maximum for ______

EASY

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

The energy gap is much more in silicon than in germanium because

MEDIUM

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

On the basis of band theory, distinguish among insulator, semiconductor, and conductor of electricity.

MEDIUM

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

Consider the statements
In a semi conductor
(A) There are no free electrons at

0 K

.
(B) There are no free electrons at any temperature
(C) The number of free electrons increases with temperature,
(D) The number of free electrons is less than that in a conductor.

MEDIUM

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

The conductivity of a semiconductor sample having electron concentration of

5 \times 10^{18} electrons m^{- 3}

, hole concentration of

5 \times 10^{19} holes m^{- 3}

, electron mobility of

2 .0 m^{2} V^{- 1} s^{- 1}

and hole mobility of

0.01 m^{2} V^{- 1} s^{- 1}

is

(Take charge of an electron as

1 .6 \times 10^{- 19} C

)

EASY

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

Consider a situation in which reverse biased current of a particular

P - N

junction increases when it is exposed to a light of wavelength

\leq 621 nm .

During this process, enhancement in carrier concentration takes place due to generation of hole-electron pairs. The value of band gap is nearly.

EASY

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

The scientific principle involved in 'Laser' is____

MEDIUM

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

Mobility of electrons in a semiconductor is defined as the ratio of their drift velocity to the applied electric field. If, for an

N

-type semiconductor, the density of electrons is

10^{19} m^{- 3}

and their mobility is

1.6 m^{2} V^{- 1} s^{- 1}

, then the resistivity of the semiconductor (since it is an

N

-type semiconductor contribution of holes is ignored) is close to:

EASY

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

Which of the energy band diagrams shown in the figure corresponds to that of a semiconductor?

HARD

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

A signal of $5 kHz$ frequency is amplitude modulated on a carrier wave of frequency $2 MHz$ . The frequencies of the resultant signal is/are:

EASY

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

The band gaps of an insulator, semiconductor and conductor are respectively $E_{g_{1},} E_{g_{2}} and E_{g_{3}}$ .The relationship between them can be given as:

HARD

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

A diode detector is used to detect an amplitude modulated wave of 60% modulation by using a condenser of capacity 250 pico farad in parallel with a load resistance of 100 kilo ohm. Find the maximum modulated frequency which could be detected by it.

MEDIUM

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

A transmitting antenna at the top of a tower has a height $32 m$ and the height of the receiving antenna is $50 m$ . What is the maximum distance between them for satisfactory communication in line of sight (LOS) mode?

MEDIUM

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

An n-p-n transistor has three leads A, B and C. Connecting B and C by moist fingers, A to the positive lead of an ammeter, and C to the negative lead of the ammeter, one finds large deflection. Then, A, B and C refer respectively to :

EASY

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

The energy band gap of semiconducting material to produce violet (wavelength

= 4000 Å

) LED is _____

eV

. (Round off to the nearest integer).

EASY

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

The band gaps of an insulator, conductor and semiconductor are respectively

E_{g 1}, E_{g 2}

and

E_{g 3} .

The relationship between them is given as _____.

EASY

Physical Sciences>Waves and Their Applications in Technologies for Information Transfer>Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.>Wave Properties - [From the 3–5 grade band endpoints] Waves can add or cancel one another as they cross, depending on their relative phase (i.e., relative position of peaks and troughs of the waves), but they emerge unaffected by each other. (Boundary: The discussion at this grade level is qualitative only; it can be based on the fact that two different sounds can pass a location in different directions without getting mixed up.)

The band gap in

Ge

and

Si

in

eV

respectively is

What is valence band and conduction band ?

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