In Young's double-slit experiment, bright fringes occur where the path difference is a half-integer number of wavelengths.

False

False. Whole-wavelength path differences arrive in phase and give the bright fringes; half-integer differences arrive antiphase and give the dark ones. Getting the condition the wrong way round inverts the entire pattern, and the fringe spacing $\lambda L/d$ is what turns it into a measurement of wavelength.