Question

In young double slit exp the slits are placed 0.320 mm apart light of wavelength i 500 nm is incident on the slit the total no of bright fringh observed is

Answer 1

distance between slits , d = 0.32mm = 3.2 × 10^-4 m

used monochromatic wave of wavelength , $\lambda$ = 500nm = 5 × 10^-7 m

you forgot to write angular range e.g., $-30^{\circ} < \theta < 30^{\circ}$

using formula,

$dsin\theta=n\lambda$

where n denotes number of bright fringe observe in YDSE.

putting all values ,

3.2 × 10^-4 sin30° = n × 5 × 10^-7

or, n = 320

hence, number of bright fringe observe 320