Cracking the SAT Physics Subject Test

CHAPTER 15 DRILL

1. B From the equation λf = c, we find that


2. D Since the fringe is bright, the waves must interfere constructively. This
   implies that the difference in path lengths must be a whole number times the
   wavelength, eliminating (B), (C), and (E). The central maximum is
   equidistant from the two slits, so ∆ℓ = 0 there. At the first bright fringe above
   the central maximum, we have ∆ℓ = λ.


3. C First, eliminate (A) and (B): The index of refraction is never smaller than 1.
   Refer to the following diagram: