Lasers are highly collimated (unidirectional), enabling precise long-distance measurements; coherence and monochromaticity also help but unidirectionality is key.
1442
Young's double slit experiment distance between 2 sources is 0.1 mm. The distance of screen from the sources is 20 cm. Wavelength of light used is 5460 Å. Then angular position of first dark fringe is
Wavelength in medium is λ0/μ, so fringe width β = Dλ/d decreases when experiment is performed in water (μ>1).
1444
The incident light on a Young's experiment has wavelengths 400 nm and 600 nm. The distance between the two interfering sources is 2 mm and the screen is at a distance of 1 m. The position where the bright fringes of the two wavelengths coincide first is at a distance of:
A slab introduces an additional path difference shifting the entire fringe system without changing fringe width (λ and D,d unchanged).
1448
In a Young's double slit experiment the fringes are displaced by a distance x when a glass plate of refractive index 1.5 is introduced in the path of one of the beams. When this plate is replaced by another plate of the same thickness, the shift of fringes is 2x. The refractive index of the 2nd plate is
Interference redistributes energy: bright fringes correspond to constructive interference and dark fringes to destructive interference, conserving total energy.
1450
Maximum number of orders available with a grating is ____ grating element.
Maximum diffraction order is limited by λ ≤ a × m, so smaller grating element a (spacing) allows more orders; thus it is inversely proportional to the grating element.
