( $a$ ) Find the normal Zeeman energy shift $\Delta E=e \hbar B / 2 m_{e}$ for a magnetic field of strength $B=0.05 \mathrm{~T} .(b)$ Use the result of Problem $7-62$ to calculate the wavelength changes for the singlet transition in mercury of wavelength $\lambda=579.07 \mathrm{nm}$.
(c) If the smallest wavelength change that can be measured in a spectrometer is $0.01 \mathrm{nm}$, what is the strength of the magnetic field needed to observe the Zeeman effect in this transition?