The transition that produced red light was caused by an electron jumping the shortest distance.
Visible light is made up of seven wavelengths the magnitude of the wavelength of a transition reflects the energy associated with such transition. The longer the wavelength shorter the transition that produced it.
Given that three lines in the visible spectrum produced three lines as follows;
Red - 625 - 740 nm
Yellow - 565 - 590 nm
Blue - 445 - 520 nm
We can see that the longest wavelength corresponds to red light hence it was caused by an electron jumping the shortest distance.
It traveled 200 m in 50 seconds. 200/50 can be simplified to 4 m/s! The velocity is -4 m/s (negative because it travelled from 100 to -100 or backwards)
