Assertion: The semiconductor used for fabrication of visible LEDs must at least have a band gap of 1.8 eV. Reason: The spectral range of visible light

Monjur Alahi

Assertion: The semiconductor used for fabrication of visible LEDs must at least have a band gap of 1.8 eV.
Reason: The spectral range of visible light is 0.4 eV to 1.8 eV
A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true not but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false
D. If both assertion and reason are false.


0 like 0 dislike
1 views
Share with your friends

1 Answers

Salim Ahmed Kawsar

Call

Correct Answer - C
The spectral range of visible light is from about 3 eV to 1.8 eV. Therefore the semiconductor used for fabrication of visible LEDs must at least have a band gap of 1.8 eV

0 like 0 dislike
1 views
Talk Doctor Online in Bissoy App
A piece of n-type semiconductor is sunjected to an electric E. The left end of the semiconductor is exposed to a radiation so that electron-hole pairs

Correct Answer - B `J_(e)=enmu_(e)E_(x)+eD_(e)(dn)/(dx)` `IL^(-2)=(ITL^(-3)(mu_(e))MLT^(-2))/(IT)+IT(D_(e))(1)/(L^(4))` `mu_(e)=[M^(-1)IT^(2)]` `D_(e)=[L^(2)t^(-1)]`

2 Answers 1 views
Some cells do not have gap phase in their cell cycle whereas some cells spend maximum part of their life in gap phase.

1. G0 is the phase of the cell cycle in eukaryotes in which many cell types stop dividing. It is also called a quiescent stage.  2. If cells are deprived of...

2 Answers 1 views
About `6%` of the power of a 100 W light bulb is converted ot visible radiation. The average intensity of visible radiation at a distance of 8 m is (A

Correct Answer - C Here , power of bulb `=100 W` As intensity, `I = ("Power of visible light")/("area")` `= (100 xx 6//100)/(4pi(8)^(2)) = 7.2 xx 10^(-3) W m^(-2)`

2 Answers 1 views
If the energy of a photon of sodium light ( `lambda`=589 nm) equals the band gap of semiconductor, the minimum energy required to create hole electron

Correct Answer - B Using ,`E=E_g=(hc)/lambda` `=(6.6xx10^(-34)xx3xx10^8)/(589xx10^(-9))J` `=(6.6xx10^(-34)xx3xx10^8)/(589xx10^(-9)xx1.6xx10^(-19))`eV =2.1 eV

2 Answers 2 views
Find the wavelength of light that may excite an electron in the valence band of diamond to the conduction band. The energy gap is 5.50 eV

Correct Answer - A Energy gap, `E_g=(hc)/lambda, lambda=(hc)/E_g` Here energy gap=5.50 eV Take hc=1240 eV nm `therefore lambda=(1240 eV nm) /(5.5 eV)=226 nm`

2 Answers 1 views
Assertion: If there is some gap between the conduction band and the valence band, electrons in the valence band all remain bound and no free electrons

Correct Answer - C If there is some gap between the conduction band and the valance band electrons in the valance band all remain bound and no free electrons in conduction...

2 Answers 1 views
Assertion : In a semiconductor, the conduction electrons have a higher mobility than holes. Reason: The electrons experience fewer collisions.

Correct Answer - C Electrons experience much collisions. The mobility of electrons is more because they require less energy to move, not because they are lighter.

2 Answers 1 views
Assertion: The probability of electrons to be found in the conduction band of an intrinsic semiconductor at a finite temperature decrease exponentiall

Correct Answer - A To jump from valence band to conduction band electron needs energy equal or more than the forbidden band between these two bands. As the energy of band...

2 Answers 1 views
Assertion: The conductivity of an intrinsic semiconductor depends on its temperature. Reason The conductivity of an intrinsic semiconductor is slightl

Correct Answer - C The conductivity of an intrinsic semiconductor is less than that of a lightly doped p-type semiconductor.

2 Answers 1 views
In H-atom, angular momentum of electron in certain orbit is `(h)/(0.5pi)` then find maximum wave number corresponding to spectral line in the visible

Correct Answer - D Cation at `3^(@) gt 2^(@) gt 1^(@)`

2 Answers 1 views
X