Question

Find the wavelength of the balmer series spectral line corresponding to n = 15.

Answer 1

371.2 mm

Step-by-step explanation:

The Balmer series of spectral lines is obtained from the formula

1/λ = R(1/2² -1/n²) where λ = wavelength, R = Rydberg's constant = 1.097 × 10⁷ m⁻¹

when n = 15

1/λ = 1.097 × 10⁷ m⁻¹(1/2² -1/15²)

= 1.097 × 10⁷ m⁻¹(1/4 -1/225)

= 1.097 × 10⁷ m⁻¹(0.25 - 0.0044)

= 1.097 × 10⁷ m⁻¹ 0.245556

= 2.693 10⁶ m⁻¹

So,

λ = 1/2.693 10⁶ m⁻¹

= 0.3712 10⁻⁶ m

= 371.2 mm