HELP WITH A CHEM QUESTION PLEASE!!! LIGHT AND WAVES!!!!

Question

The question is what is the weight of Orange (590 nm) in nanograms (ng)?

 

What is the answer to the question and how would you find this?

 

Answer 1

Dear Psalm,

 

I must start by saying that your instructor doesn't understand what it is that he/she is teaching because light has no mass and much less weight. I presume that the misunderstanding of what Einstein's equation predicts is the reason for this kind of question.

 

Technically, E = mc^2 only applies to mass particles, but for the sake of this problem we'll pretend that it applies. However, I do want to make sure that you understand this calculation is completely meaningless and has no physical truth to it whatsoever.

 

First determine the energy of orange light using Planck's equation:

 

E = hc/L

 

now substitute into Einstein's equation:

 

mc^2 = hc/L

 

solve for m:

 

m = h/cL = [(6.626x10^-34 Kgm^2/s)/(2.998x10^8 m/s)(5.90x10^-7 m)] = 3.75x10^-36 kg or 3.75x10^-24 ng

 

Once again, this is the answer to your question using completely misunderstood equations.