Modifying Slit Separation for Seeing Fringes Again | 65 Characters

[desmond iking]

Homework Statement

i can't understand part b ii) , i assume the resolving power of eyes is constant . so when the slit separation increase , the wavelength of the light should be decreased to keep the tetha ( here , tetha = resloving power of eyes in radian )...But the book give different ideas . Can someone explain on this?

Homework Equations

The Attempt at a Solution

 

[andrevdh]

The fringes are formed closer together when the slits are further apart.
The solution calculates when they will just be resolved by the eye, but
not seen "clearly". That is theta need to be increased even more to be
able to see the fringes clearly. If the same double slit is to be used all
that can be done is to increase the wavelength to obtain a larger theta.