Given: fringe with b = 0.03 cm, D = 1 m = 100 cm Distance between images of the source = 0.8 cm. Image distance v = 80 cm Object distance = u Using mirror formula
1
v
+
1
u
=
1
f
⇒
1
60
+
1
u
=
1
16
⇒ u = 20 cm Magnification, m =
v
u
=
80
20
= 4 Magnification =
distances‌between‌images‌of‌slits
distance‌between‌slits
=
0.8
d
= 4 ⇒ d = 0.2 cm Fringe width β =
Dλ
d
or , β =
100λ
0.2
= 0.03 × 10−2 Therefore, wavelength of light used λ = 6000 Å