In a double slit interference experiment, the separation between the slits is 1⋅0 mm, the wavelength of light used is 5⋅0 × 10−7 m and the distance of the screen from the slits is 1⋅0 m. (a) Find the distance of the centre of the first minimum from the centre of the central maximum. (b) How many bright fringes are formed in one centimetre width on the screen?
Answers
Answer:
a)the distance of the centre of the first minimum from the centre of the central maximum is 0.25 mm
b)number of bright fringes formed in one centimetre (10 mm) =10/0.50
=20
Explanation:
Separation between the two slits = d=1 mm=10⁻³ m
Wavelength of the light used=λ=5.0×10⁻⁷m
Distance between screen and slit, D=1 m
(a) The distance of the centre of the first minimum from the centre of the central maximum,
Formula :
x = width of central maxima /2
x=β/2=λD/2d …(i)
=5×10⁻⁷×1/2×10⁻³
=2.5×10⁻⁴ m=0.25 mm
(b)How many bright fringes are formed in one centimetre width on the screen:
From equation (i),
fringe width =β=2xX=2x0.25=0.50 mm
So, number of bright fringes formed in one centimetre (10 mm) =10/0.50
=20
Answer:
Given that,
The distance between the slits is d=1 mm=10
−3
m
The distance of central maximum, from slit D=1 m.
The wavelength of the light used is 5×10
−7
m
So, fringe with is given as
β=
d
Dλ
10
−3
1×5×10
−7
=0.5 mm.
No. of fringes in 1cm =
0.5
10
=20.