How Many Spectral Lines in the Balmer Series Exceed 400 nm?

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Homework Help Overview

The discussion revolves around determining how many spectral lines in the Balmer series exceed a wavelength of 400 nm. The Balmer series pertains to the visible light spectrum emitted by hydrogen and involves calculations related to the wavelengths of emitted light as electrons transition between energy levels.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between the principal quantum number n and the corresponding wavelengths, questioning how far to calculate n to find all relevant spectral lines. There is also a discussion about the nature of the Balmer series and its limits.

Discussion Status

Some participants have provided guidance on using the formula for calculating wavelengths and suggested that only a few calculations may be necessary to answer the original question. There is an acknowledgment of the infinite nature of the series, but clarity on practical limits for calculations is being sought.

Contextual Notes

The original poster notes confusion regarding the starting point and the extent of calculations needed, indicating a potential gap in understanding the series' behavior as n increases.

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Homework Statement



In the Balmer series, how many spectral lines have the wavelength greater than 400 nm?

Homework Equations



1/lambda= R(1/2^2-1/n^2)
lambda=wavelength
r=rhydberg constant 1.097x10^7
n= 3,4,5...
balmer series is visible light

The Attempt at a Solution



ok so i know the balmer series starts with 400 nanometers because its visible light, but i don't understand how to see how many spectral lines have wavelength greater.
 
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You could just look up the Balmer Series in a book or on the web and count them.
Or use the formula to calculate the wavelengths - put in n=3, calculate. Put in n=4, calculate. Pretty soon you will have all the wavelengths you need!
 
ok. but when i do the calculating up to what number do i go? because i thought it went from 2 on.
 
Yes, it does go on forever - 2 to infinity. But after calculating 2 or 3 wavelengths, you will see that you don't have to do very many of them the answer your question.
 
o ok i got it. wavelength decreases when you increase n
thanks appreciate your response
 

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