Two  coherent radio sources that are separated by 2m are radiating in phase with a wavelength of 0.25m. If a detector moves in a large circle around their midpoint. At how many points will the detector show a maximum signal?

At A and C, Δx=d=8λ, i.e. maximum intensity is obtained.
Between A and B seven maximas corresponding to Δx=7λ,6λ,5λ,4λ,3λ,2λ and λ will be obtained. 

Similarly, between B and C, C and D and D and A.
∴ Total number of maximas
=4×7+4
= 32