The answer would be it will be longer than the 656.3 nm. The reduced mass of positronium is less than hydrogen so the photon energy will be a reduced amount of for positronium than for hydrogen. So this will mean that the wavelength will be lengthier.
Their is no document for us to look at , can you add it so i can help you
To solve this problem it is necessary to apply the concepts related to the principle of superposition and the equations of destructive and constructive interference.
Constructive interference can be defined as
Where
m= Any integer which represent the number of repetition of spectrum
= Wavelength
d = Distance between the slits.
= Angle between the difraccion paterns and the source of light
Re-arrange to find the distance between the slits we have,
Therefore the number of lines per millimeter would be given as
Therefore the number of the lines from the grating to the center of the diffraction pattern are 380lines per mm
The control setup in this experiment would be one tank that does not contain any of the additives. Since the tanks with the gasoline additives would need to be compared with a tank that is not affected by the results of these additives.