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Physics problem, might just be a calculator problem?
Chop Logic
Registered User regular
Registered User regular
So the question is:
Calculate the energy of the transitions from the n = 4,5,6 energy levels to the n = 3 level for the hydrogen atom using the Bohr formula.
I'm assuming he means this equation (sorry, I'll just write this phonetically because I don't have any idea how to write the symbols):
Delta E = ((e^2)(m sub e) / 8 Epsilon^2 h^2))((1/n sub f ^2) - (1/n sub i^2))
The problem is, the numerator of the first part of the equation, e^2(m sub e) , is so small that on the three calculators I've tried, it just works out to zero, and the whole equation becomes zero.
Am I doing this right? It's pretty frustrating because this is the first problem in a long list of problems and if I can't get this answer I can't do the rest of the problems, but I can't figure out what I should be doing.
Thanks a lot.
Calculate the energy of the transitions from the n = 4,5,6 energy levels to the n = 3 level for the hydrogen atom using the Bohr formula.
I'm assuming he means this equation (sorry, I'll just write this phonetically because I don't have any idea how to write the symbols):
Delta E = ((e^2)(m sub e) / 8 Epsilon^2 h^2))((1/n sub f ^2) - (1/n sub i^2))
The problem is, the numerator of the first part of the equation, e^2(m sub e) , is so small that on the three calculators I've tried, it just works out to zero, and the whole equation becomes zero.
Am I doing this right? It's pretty frustrating because this is the first problem in a long list of problems and if I can't get this answer I can't do the rest of the problems, but I can't figure out what I should be doing.
Thanks a lot.
Chop Logic on
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Posts
Do I just need to buy one of those expensive TI calculators? I am using a scientific calculator I borrowed from my roommate and even that is giving me zeros.
take that 10^-34 and multiply it in at the end.
whats the actual value of the very small number?
also, what is the value of the other part as well.
Edit: One second, I will write out a more accurate description of what is happening.
So I'm putting it in in pieces.
The first part, (e^4)(m sub e) , is:
(1.6 x 10^-19)^4 (9.11 x 10^-31)
When I put it into the calculator, I keep getting zero as an answer. I think it's because the number is so small that the calculator is rounding it down to zero, but even the scientific calculator is doing that. What should I do?
Edit: I changed the mode on the scientific calculator, and now it's giving me 0 x 10^00 . Awesome.
and you want to find x. y = 5 and z = 1x10^-100. when you put this into a calculator it will give you a zero. the most accurate answer though is (5x1)x10^-100 or 5x10^-100.
if y = 5x10^50, then it would be (5x1)x10^(50-100) or 5x10^-50
Also, yes, the answer will be quite small indeed. I think your formula gives you someting in Joules. In this case, it would probably be better to convert it so you get the answer in eV. But if I just lost you, don't worry about it.
Nintendo Network ID: PhysiMarc
the answer is (1.6x9.11)x10^(-31-19) or 14.576x10^-50
I also found a setting to change all answers into scientific notation, and now it's giving me 0 ^ 0.
give the numbers.
YES. This worked.
Thanks a lot everyone for helping me out.
You can also do some algebra:
(1.6 x 10^-19)^4 (9.11 x 10^-31)
=
(1.6^4) x (10^-19)^4 x (9.11 x 10^-31)
=
(1.6^4x9.11) x (10^-19)^4 x (10^-31)
and go from there. The problem you were having with your scientific calculator is clear - once you multiply that out, your exponent on the 10 is less than -100. Most calculators can only handle exponents on the 10 in scientific notation between -100 and 100.
just so you know, when you multiply numbers with exponents that have the same base, you add the exponents and keep the base
10^3 x 10^3 (which is 1000x1000) does not equal 10^9 (1,000,000,000) but 10^6 (1,000,000)
Right, so the result would be
59.703296x10^-107
=
5.9703296x10^-106
The trick is to break it down into parts, and alternate entering a part from the numerator and from the denominator. Breaking it into parts doesn't work if you enter all of the denominator parts consecutively.