## Remote Sensing C

hearthstone224
Member
Posts: 132
Joined: October 13th, 2016, 1:50 pm
Division: C
State: IL

### Re: Remote Sensing C

End of freshman season. Good luck to everyone! No state for us, but nevertheless great season. Regional was out of 12 teams. (CLC)

Mat Sci-> Second at regionals
RSensing -> First at regionals
Towers-> Third at regionals.

Xuax
Member
Posts: 16
Joined: February 26th, 2017, 11:33 am
Division: C
State: -

### Re: Remote Sensing C

What is the peak wavelength of a blackbody at temperature 310 K?

hearthstone224
Member
Posts: 132
Joined: October 13th, 2016, 1:50 pm
Division: C
State: IL

### Re: Remote Sensing C

What is the peak wavelength of a blackbody at temperature 310 K?
You can use Wein's law so you can do:

0.29/310K = 0.000935483871 nm. That's in the gamma ray range I think.
End of freshman season. Good luck to everyone! No state for us, but nevertheless great season. Regional was out of 12 teams. (CLC)

Mat Sci-> Second at regionals
RSensing -> First at regionals
Towers-> Third at regionals.

Private Wang Fire
Member
Posts: 100
Joined: June 1st, 2015, 3:43 pm
State: OH

### Re: Remote Sensing C

What is the peak wavelength of a blackbody at temperature 310 K?
You can use Wein's law so you can do:

0.29/310K = 0.000935483871 nm. That's in the gamma ray range I think.
Er, either your units out constant are incorrect I think. No way the wavelength is that low at 310K.
MASON HIGH SCHOOL '18

Xuax
Member
Posts: 16
Joined: February 26th, 2017, 11:33 am
Division: C
State: -

### Re: Remote Sensing C

What is the peak wavelength of a blackbody at temperature 310 K?
You can use Wein's law so you can do:

0.29/310K = 0.000935483871 nm. That's in the gamma ray range I think.
Er, either your units out constant are incorrect I think. No way the wavelength is that low at 310K.
If that was in centimeters, it would be correct. Remember, Wien's displacement constant is 2.8977729 × 10^-3 m K. That divided by 310 K gives 9.34765452e-6 m, which in nm is 9347.6 nm.

hearthstone224
Member
Posts: 132
Joined: October 13th, 2016, 1:50 pm
Division: C
State: IL

### Re: Remote Sensing C

Ah, well I never knew the constant's units. Thanks. So to confirm- This would be in the infared range.

Do I get next question? If so, I'll just let someone else do it (If that is allowed. I can't think of one rn).
End of freshman season. Good luck to everyone! No state for us, but nevertheless great season. Regional was out of 12 teams. (CLC)

Mat Sci-> Second at regionals
RSensing -> First at regionals
Towers-> Third at regionals.

Xuax
Member
Posts: 16
Joined: February 26th, 2017, 11:33 am
Division: C
State: -

### Re: Remote Sensing C

Ah, well I never knew the constant's units. Thanks. So to confirm- This would be in the infared range.

Do I get next question? If so, I'll just let someone else do it (If that is allowed. I can't think of one rn).
It would be in the infrared (LWIR). I'll ask the next question.

What temperature must a blackbody with 5.54* 10^-28 W × sr-1 × m-3 spectral radiance and 550 nm wavelength be at?

hearthstone224
Member
Posts: 132
Joined: October 13th, 2016, 1:50 pm
Division: C
State: IL

### Re: Remote Sensing C

Ah, well I never knew the constant's units. Thanks. So to confirm- This would be in the infared range.

Do I get next question? If so, I'll just let someone else do it (If that is allowed. I can't think of one rn).
It would be in the infrared (LWIR). I'll ask the next question.

What temperature must a blackbody with 5.54* 10^-28 W × sr-1 × m-3 spectral radiance and 550 nm wavelength be at?
Alright. I have an idea, but I'm confused on how we would use the wavelength information.

Stefan-Boltzmann's law states that L = A*alpha*T^4, where L is the luminosity, A is the surface area, alpha is the constant 5.670*10^-5 and then T is what we are looking for. We only lack the surface area information here.

How would we figure that out? Am I on the right track?
End of freshman season. Good luck to everyone! No state for us, but nevertheless great season. Regional was out of 12 teams. (CLC)

Mat Sci-> Second at regionals
RSensing -> First at regionals
Towers-> Third at regionals.

Unome
Moderator
Posts: 4084
Joined: January 26th, 2014, 12:48 pm
State: GA
Location: somewhere in the sciolyverse

### Re: Remote Sensing C

Ah, well I never knew the constant's units. Thanks. So to confirm- This would be in the infared range.

Do I get next question? If so, I'll just let someone else do it (If that is allowed. I can't think of one rn).
It would be in the infrared (LWIR). I'll ask the next question.

What temperature must a blackbody with 5.54* 10^-28 W × sr-1 × m-3 spectral radiance and 550 nm wavelength be at?
Alright. I have an idea, but I'm confused on how we would use the wavelength information.

Stefan-Boltzmann's law states that L = A*alpha*T^4, where L is the luminosity, A is the surface area, alpha is the constant 5.670*10^-5 and then T is what we are looking for. We only lack the surface area information here.

How would we figure that out? Am I on the right track?
I suspect Xuax meant to say W x sr-1 x m-2 which is the correct unit for spectral radiance. Somehow you would have to get rid of the steradian (maybe multiply by the number of steradians per sphere?) and then use the flux form of Stefan-Boltzmann's Law: $F =\sigma * T^4$. As far as I know, the wavelength is unneeded for the problem (though I guess you can alternatively solve it using Wien's Law?)
Userpage
Chattahoochee High School Class of 2018
Georgia Tech Class of 2022

Opinions expressed on this site are not official; the only place for official rules changes and FAQs is soinc.org.

Xuax
Member
Posts: 16
Joined: February 26th, 2017, 11:33 am
Division: C
State: -

### Re: Remote Sensing C

It would be in the infrared (LWIR). I'll ask the next question.

What temperature must a blackbody with 5.54* 10^-28 W × sr-1 × m-3 spectral radiance and 550 nm wavelength be at?
Alright. I have an idea, but I'm confused on how we would use the wavelength information.

Stefan-Boltzmann's law states that L = A*alpha*T^4, where L is the luminosity, A is the surface area, alpha is the constant 5.670*10^-5 and then T is what we are looking for. We only lack the surface area information here.

How would we figure that out? Am I on the right track?
I suspect Xuax meant to say W x sr-1 x m-2 which is the correct unit for spectral radiance. Somehow you would have to get rid of the steradian (maybe multiply by the number of steradians per sphere?) and then use the flux form of Stefan-Boltzmann's Law: $F =\sigma * T^4$. As far as I know, the wavelength is unneeded for the problem (though I guess you can alternatively solve it using Wien's Law?)
The question was supposed to be about the Planck function. When the function is expressed as Bλ(λ,T), the unit is W x sr-1 x m-3. That is a unit of spectral radiance. If you know the spectral radiance and the wavelength, you can find the temperature.

Xuax
Member
Posts: 16
Joined: February 26th, 2017, 11:33 am
Division: C
State: -

### Re: Remote Sensing C

Use the form of Planck´s function tλ(λ,L) to find the answer.

jonboyage
Member
Posts: 102
Joined: December 13th, 2016, 8:32 am
State: PA

### Re: Remote Sensing C

I didn't realize this wasn't answered yet...
Is it
I was in a bin

Rustin '19
UPenn '23

Asphalt
Member
Posts: 2
Joined: March 27th, 2017, 6:42 pm
State: -

### Re: Remote Sensing C

Short Event Description: Participants will use remote sensing imagery, data and computational process skills to complete tasks related to climate change processes in the Earth system.

What is the difference between active and passive sensing?
This is a great question to start with because it will be on literally every Remote Sensing test you take this year. Know the answer to this question.
Passive: Detects natural energy reflected/Emitted from an observed scene
Active: Detects own radiation reflected back to instrument

Asphalt
Member
Posts: 2
Joined: March 27th, 2017, 6:42 pm
State: -

### Re: Remote Sensing C

Use the form of Planck´s function tλ(λ,L) to find the answer.
Is this what i would do?

Planck Quanta (Q) Equal to hv [variable( h ) constant equal to 6.63 x 10 to the negative 34th power] [J-s & v variable represents frequency in 1/s]
Planck Unknown Known: Frequency (v) wavelength Energy ( E )

if so how?

whythelongface
Exalted Member
Posts: 326
Joined: March 12th, 2017, 7:42 pm
State: NJ

### Re: Remote Sensing C

No. Planck's Function is:

So you would plug the values for B_λ and λ in and solve for T.

Sorry for being late, but I thought the thread needed reviving.
WEST WINDSOR-PLAINSBORO HIGH SCHOOL SOUTH '18
EMORY UNIVERSITY '22
SONT 2017 5th Place Medalist [Microbe Mission]

"One little Sciolyer left all alone,
He went out and hanged himself and then there were none."

Congratulations to WW-P South for winning 14th place at Nationals!