Posted by Odesa on Friday, December 14, 2012 at 1:16am.
The glass panels of a sky roof need to be coated in order to screen out ultraviolet radiation (10-400 nm wavelength) but without color distortion in the visible spectrum. Candidate coating materials are gallium nitride (GaN) with a band gap,Eg, of 3.2 eV, or gallium arsenide (GaAs) with a band gap, Eg, of 1.34 eV. Choose the best explanation for which of these materials, if either, will work.
DATA: representative wavelengths associated with different colors in the visible spectrum:
violet 425 nm
blue 475 nm
green 535 nm
yellow 590 nm
orange 610 nm
red 700 nm
I)GaAs is the best choice, it has a band gap low enough to block out UV radiation while allowing visible light to pass.
II)GaN is the best choice, it has a band gap low enough to block out UV radiation while allowing visible light to pass.
III)Neither will work, due to the electromagnetic spectrum any material that blocks out UV radiation will also block out visible light, this is why sunscreen and sunglasses tend to be somewhat opaque.
IV)Neither will work, UV light will be able to pass through both of them if visible light is able to pass through as well.
V)Neither will work, visible light has energy greater than 3 eV and the semiconductors will be opaque.
VI)Both will work, visible light has energy lower than 1 eV and is able to pass through both materials unaltered.
- Chemistry - Anonymous, Friday, December 14, 2012 at 4:18am
I
- Chemistry - Anonymous, Friday, December 14, 2012 at 4:29am
I is wrong answer
- Chemistry - Anonymous, Friday, December 14, 2012 at 4:35am
Someone please answer this ;(
- Chemistry - Yamy, Friday, December 14, 2012 at 4:36am
I agree I) is wrong
- Chemistry - Anonymous, Friday, December 14, 2012 at 4:59am
I got green with IV
- Chemistry - mike, Friday, December 14, 2012 at 5:05am
IV)Wrong !Neither will work, UV light will be able to pass through both of them if visible light is able to pass through as well.
- Chemistry - Paul, Friday, December 14, 2012 at 5:29am
Got it wrong for IV), hmm wonder why folks are messing with the answers.
- Chemistry - Anonymous, Friday, December 14, 2012 at 5:44am
II
- Chemistry - Anonima, Friday, December 14, 2012 at 9:31am
The correct answer is II
- Chemistry - Odesa, Sunday, December 16, 2012 at 10:44pm
Thank you Anonymous and Anonima
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