Question

Heat treatment of muscular pain involves radiation of a wavelength of about 900 nm. Which spectral line of H-atom is suitable for this purpose?
[RH=1×105cm−1,h=6.6×10−34Js,c=3×108ms−1]

• A. Paschen, $5\to 3$
• B. Paschen, $\infty \to 3$
• C. Lyman, $\infty \to 1$
• D. Balmer, $\infty \to 2$

Answer 1

The correct option is D Paschen, ∞→3
We have,

1λ=RZ2(1nl2−1nf2)

Here if nl=3 and nf=∞

1λ=10−7×12(132−1∞2)=10−79=900nm

So, the correct option is B