The yellow sodium D lines have wavelengths of 589.0 nm and 589.6 nm. When they are used to illuminate a Michelson interferometer, it is noted that the interference fringes disappear and reappear periodically as the mirror M1 is moved. Why does this happen? How far must the mirror move between one disappearance and the next?

i don't understand. explain it clearly

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.

in order to follow the instructions and complete the statements, i need to use data from table c of your student guide. can you think of a way to let me see your student guide for a while ? i can't answer the question without the data in table c.