Chapter 35, Problem 24P

In Fig. 35-39, two isotropic point sources S₁ and S₂ emit light in phase at wavelength λ and at the same amplitude. The sources are separated by distance 2d = 6.00λ. They lie on an axis that is parallel to an x axis, which runs along a viewing screen at distance D = 20.0λ. The origin lies on the perpendicular bisector between the sources. The figure shows two rays reaching point P on the screen, at position x_P. (a) At what value of x_p do the rays have the minimum possible phase difference? (b) What multiple of λ gives that minimum phase difference? (c) At what value of x_p do the rays have the maximum possible phase difference? What multiple of A gives (d) that maximum phase difference and (e) the phase difference when x_P = 6.00λ? (f) When x_P = 6.00λ, is the resulting intensity at point P maximum, minimum, intermediate but closer to maximum, or intermediate but closer to minimum?

Figure 35-39 Problem 24