Red light, of wavelength 600 nm, passes through a double slit. A pattern appears on a screen 3.0 m away. What is the distance between the 1st and 4th nodal lines, of the slits are 4.0 x 10-5 m apart?
Can anyone give a clear answer?
d*q_n.....n*wl....these formulas are not common (google search doesn't help me with these formula's). Can anyone give a clear answer with commonly used formulas?
nyphdinmd
Favorite Answer
The bright fringes appear at
d*q_n = n*wl n = 0 ,1, 2, 3 ...
q_n = angle nth fringe makes with optical axis
d = distance to betwen slits
wl = wavelength of light
let y_n = position of the nth bright spot on a screen D meters away. Then
y_n = D*q_n = n*wl*D/d
Distance between two fringes, m and n, on the screen is
Y_mn = |y_m - y_n| = |m - n|*D*wl/d --> the | | are used so if n > m you get a positive number
Set m = 4, n = 1, d = 4x10^-5m and wl = 600 nm. For ease of computing
d = 40 um and wl = 0.6um then for D = 3m
Y_14 = 3*0.6/40 = 0.045 m