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?

[R_H = 1 × 10⁵ cm⁻¹, h = 6.6 × 10⁻³⁴ Js, c = 3 × 10⁸ ms⁻¹]

विकल्प

• Paschen, `∞ -> 3`

• Paschen, `5 -> 3`

• Balmer, `∞ -> 2`

• Lyman, `∞ -> 1`

Answer 1

Paschen, `bb(∞ -> 3)`

Explanation:

`1/λ = "R"_"H"(1/"n"_1^2 - 1/"n"_2^2)`

n₁ = 3, n₂ = `∞`

`1/λ = "R"_"H"(1/9)`

λ = `9/"R"_"H"`

= `9/10^5`

= 9 × 10⁻⁵ cm

= 900 nm