Kapil Khare
Last Activity: 5 Years ago
Let D be distance between slit and the screen.
Let d be distances between the two slits.
Wavelength of the first wavelength = 2.5 *10-7 m
Bright fringes for the first wavelength = n(2.5 *10-7 D/d)
Wavelength of the second wavelength = 3.5 *10-7 m
Bright finges for the second wavelength = m(3.5 *10-7 D/d)
For the two fringes coincides to coincides,
m(3.5 *10-7 D/d) = n(2.5 *10-7 D/d)
7m = 5n m/n = 5/7
So, the 5
th bright fringe of second wavelength coincide with 7
th bright fringe of first wavelength
