4. In the early 1900s the normal Zeeman effect was useful to determine the electron's e/mif Planck's constant was assumed known. Calcium is an element that exhibits the normal Zeeman effect to a good approximation. The difference between adjacent components of the spectral lines is observed to be 0.0168 nm for =422.7 nm when calcium is placed in a magnetic field of 1.5 T. From these data calculate the value of eh / 2 mand compare with the accepted value today. Calculate e/musing this experimental result along with the known value of h-bar.