Question

Is i (image) positive or negative for a real image formed by a mirror? For a virtual image?

Since nf ( final energy level quantum number)can run from 1 to infinity and for an emission line, ni ( initial energy level quantum number) can run from nf (final energy level quantum number ) to infinity, there must be an infinitive number of emission lines for hydrogen.Why can you see only four in the spectrometer?

A certain grating has 7500 lines per inch. What is the highest order in which you would expect to be able to see the mercury green line?

Answer 1

if i is negative then image is virtual.

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four lines that observed falls in the range of visible light that we observe. all other transition are out of this visible light spectrum.

- n = 3 to 2 (red)
n = 4 to 2 (green)
n = 5 to 2 (blue)
n = 6 to 2 (purple)

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Mercry green light wavelength = 510 nm

a = 1 inch / 7500 lines = 0.0254 m / 7500

a = 3.39 x 10^-6 m

sin(theta_n) = n lambda / a

sin(theta) can have maximum value of 1.

n = a / lambda = 6.64

so hightest order = 6