The semiconductor used for LEDs emitting in the visible range is 

(a) GaAs (b) GaAlAs (c) GalnAs (d) GaAsP

1 Answer

Answer :

The semiconductor used for LEDs emitting in the visible range is GaAsP

Related questions

Description : Semiconductor LEDs emit incoherent light. Define incoherent light

Last Answer : Light waves that lack a fixed-phase relationship

Description : It is the made from semiconductor material such as aluminum-galium-arsenide or gallium-arsenide-phosphide. A. APD B. Injection laser diode C. Light emitting diode D. Positive-intrinsic-negative

Last Answer : C. Light emitting diode

Description : Why are visible-light LEDs not used for fiber optics? ∙ a. It has high losses ∙ b. It has short wave ∙ c. It has low attenuation ∙ d. It has weak signal

Last Answer : ∙ a. It has high losses

Description : In a single crystal of an intrinsic semiconductor, the number of free carriers at the Fermi level at room temperature is: A) Half the total number of electrons in the crystal B) Zero C) Half the number of atoms in the crystal D) Half the number of free electrons in the crystal

Last Answer : In a single crystal of an intrinsic semiconductor, the number of free carriers at the Fermi level at room temperature is: Zero 

Description : In an n-type semiconductor, as the donor concentration ND increases, the Fermi level EF: (1) Remains unaltered (2) Moves towards the conduction band (3) Move towards the center of forbidden energy gap (4) May or may not move depending on temperature 

Last Answer : In an n-type semiconductor, as the donor concentration ND increases, the Fermi level EF: Moves towards the conduction band

Description : Impurity atoms to be added to pure silicon in order to make a p-type semiconductor belongs to (a) Phosphorous (b) Boron (c) Antimony (d) Aluminium 

Last Answer : Boron  , a  group  three  element.

Description : The advantage of a semiconductor strain gauge cover the wire round strain gauge is that

Last Answer : The advantage of a semiconductor strain gauge cover the wire round strain gauge is that it is more sensitive

Description : The polar bonds existing in III-V compound semiconductor, may be considered as equivalent to  (a) 1 ionic bond and 3 covalent bonds (b) 1 ionic bond and 4 covalent bonds (c) 2 ionic bonds and 2 covalent bonds (d) 2 ionic bonds and 4 covalent bonds

Last Answer : The polar bonds existing in III-V compound semiconductor, may be considered as equivalent to 1 ionic bond and 3 covalent bonds

Description : The material used for ‘doping’ to prepare N - type semiconductor is

Last Answer : The material used for ‘doping’ to prepare N - type semiconductor is Arsenic

Description : While comparing doped semiconductor vs. un-doped semiconductor, which of the following statements is NOT true ? (A) Doped semiconductor has smaller band-gap compared to un-doped semiconductor (B) ... to un-doped semiconductor (D) Doped as well as un-doped semiconductor have equal bandwidth

Last Answer : While comparing doped semiconductor vs. un-doped semiconductor, which of the following statements is NOT true ? (A) Doped semiconductor has smaller band-gap compared to un-doped semiconductor (B) ... to un-doped semiconductor (D) Doped as well as un-doped semiconductor have equal bandwidth

Description : To increase mobility of electron in a given piece of semiconductor (A) Increase overall size of the semiconductor (B) Increase length (C) Increase width (D) Small increase in temperature above room temperature value

Last Answer : To increase mobility of electron in a given piece of semiconductor Small increase in temperature above room temperature value

Last Answer : At absolute temperature, an intrinsic semiconductor has No holes or free electrons.

Last Answer : At room temperature, an intrinsic semiconductor has A few free electrons and holes.

Last Answer :  In an intrinsic semiconductor, the number of free electrons Equals the number of holes.

Last Answer : When the temperature of an extrinsic semiconductor is increased, the pronounced effect is on Minority carriers.

Last Answer : In a semiconductor, current conduction is due to Holes and free electrons.

Last Answer : As the doping to a pure semiconductor increases, the bulk resistance of the semiconductor Decreases.

Last Answer : The impurity level in an extrinsic semiconductor is about 1 atom for 108 atoms of pure semiconductor.

Last Answer : A hole in a semiconductor is defined as The incomplete part of an electron pair bond.

Last Answer : Addition of trivalent impurity to a semiconductor creates many Holes.

Last Answer : An n-type semiconductor is Electrically neutral.

Last Answer : Addition of pentavalent impurity to a semiconductor creates many Free electrons.

Last Answer : When a pentavalent impurity is added to a pure semiconductor, it becomes n-type semiconductor.

Last Answer : The strength of a semiconductor crystal comes from Electron-pair bonds.

Last Answer : When a pure semiconductor is heated, its resistance Goes down.

Last Answer : The most commonly used semiconductor is Silicon.

Last Answer : A semiconductor has Negative temperature coefficient of resistance.

Description : Which kind of lightbulb is more energy efficient / cost efficient to operate for the same amount of light: those twisty spiral florecent bulbs or LEDs?

Last Answer : LEDs are more energy efficient and last longer

Description : Will UV LEDs work like a UV tube?

Last Answer : answer:Ahh too late to edit, I can get 385-405nm ones for super cheap, but I can see some 380nm ones for 67 cents each, woud those be better? I'm having trouble finding what the real ... , found 100 5mm LEDs, 380-385nm wavelength, only 30 bucks! I wonder if that wavelength works well though.

Description : Is my 1993 Miata Too old school for LED's?

Last Answer : It maybe the bad contact in the socket is is causing it. check your grounds. The circuit for the brake/running lights maybe causing the cruise control to malfunction. I had a Mitsubishi that ... 4 way flashers on and have the cruise control work ! Think flashing lights equal to malfunction socket.

Description : Why can't I mix and match LEDs wired in parallel?

Last Answer : answer:An LED is a diode. As such it has a forward voltage drop, i.e., when it's conducting current and shining light, there is a small voltage drop from one end to the other. (After all, with ... device & some would shine brighter than others. So it's still best to give each LED its own resistor.

Description : Why can't I mix and match LEDs wired in parallel?

Last Answer : answer:An LED is a diode. As such it has a forward voltage drop, i.e., when it's conducting current and shining light, there is a small voltage drop from one end to the other. (After all, with ... device & some would shine brighter than others. So it's still best to give each LED its own resistor.

Description : Has anyone bought loose LEDs?

Last Answer : What are you buying them for? I’ve bought them before, but I was buying them for an electronics kit type thing.

Description : Where can I find the best deals on LEDs?

Last Answer : Here!

Description : Tunnel diode is a: a) Power diode b) Has light doping c) Has heavy doping d) Is a reverse recovery diode Ans: C 76.LEDs are fabricated from: a) Silicon b) Germanium c) Si or Ge d) Gallium arsenide

Last Answer : Ans: D

Description : What is the lifetime of LEDs? a. 200,000 minutes b. 200,000 hours c. 150,000 minutes d. 150,000 hours

Last Answer : b. 200,000 hours

Description : Are the effects of temperature changes on LDs more or less significant than for LEDs?

Last Answer : More.

Description : Which types of LEDs are the preferred optical sources for short-distance, low-data-rate fiber optic systems?

Last Answer : SLEDs and ELEDs.

Description : Why are LEDs preferred over laser diodes for low- and moderate-frequency analog applications?

Last Answer : LEDs require less complex circuitry than lasers.

Description : Why can multimode graded-index fiber 1300-nm systems using LEDs operate over longer distances and at higher bandwidths than 850-nm systems?

Last Answer : Longer distances and higher bandwidths are possible because fiber material losses and dispersion are significantly reduced at the 1300-nm region.

Description : LEDs operating at 850 nm provide sufficient optical power for short-distance, low-bandwidth multimode systems. List three conditions that prevent the use of LEDs in longer distance, higher bandwidth multimode systems.

Last Answer : Multimode fiber dispersion, the relatively high fiber attenuation, and the LED's relatively low optical output power.

Description : Both LEDs and ILDs operate correctly with ∙ A. forward bias ∙ B. reverse bias ∙ C. neither forward nor reverse bias ∙ D. either forward or reverse bias

Last Answer : A. forward bias

Description : What is the typical wavelength of light emitted from epitaxially grown LEDs? ∙ a. 840 nm ∙ b. 490 nm ∙ c. 480 nm ∙ d. 940 nm

Last Answer : ∙ d. 940 nm

Description : Both LEDs and ILDs operate correctly with ∙ a. Forward bias ∙ b. Reverse bias ∙ c. Neither A or B ∙ d. Either A or B

Last Answer : a. Forward bias

Description : What is the lifetime of LEDs? ∙ a. 200,000 minutes ∙ b. 200,000 hours ∙ c. 150,000 minutes ∙ d. 150,000 hours

Last Answer : a. 200,000 minutes

Description : Both LEDs and ILDs operate correctly with:

Last Answer : Forward bias

Description : 9 leds each of 1 volt drop is series with 9  volt battery , do we need a resistor?(SMD leds) I have seen some smd leds without resistor !

Last Answer : We connect resistor to limit the current. So, it depends upon the current rating of the LED, which is provided by manufacturer.

Description : Find out number of data lines required to interface 16 LEDs arrange in the 4 x 4 matrix form.

Last Answer : 4+4=8, eight lines are required for 4x4 matrix of 16 LEDs

Last Answer : The power consumption of LEDS may be of the order of 5 to 10 milli-amperes.