A solar probe mission detects a fractional wavelength shift (∆λ/λ) of the spectral line λ = 630 nm within a sunspot to be of the order of 10^-5. Assuming this shift is caused by the normal Zeeman effect (i.e.. neglecting other physical effects). the estimated magnetic field (in tesla) within the observed sunspot is closest to

Correct option is C

Solution:

$${Zeeman\ shift\ for Normal\ Zeeman\ effect}\Delta E = \mu_B B \Rightarrow \Delta \nu = \frac{\mu_B B}{h} \Rightarrow |\Delta \lambda| = \frac{\mu_B B \lambda^2}{hc}\\\ \\\Rightarrow |\Delta \lambda| = \frac{\mu_B B \lambda^2}{hc} \Rightarrow B = \frac{|\Delta \lambda|}{\lambda} \frac{hc}{\mu_B \lambda} = \frac{10^{-5} \times 3 \times 10^8 \times 6.6 \times 10^{-34}}{9.27 \times 10^{-24} \times 630 \times 10^{-9}} = 0.33$$​