Two slits separated by a distance of 1mm are illuminated with red ligh...
Two slits separated by a distance of 1mm are illuminated with red ligh...
Given:
- Distance between the two slits (d) = 1mm = 0.001m
- Wavelength of red light (λ) = 6.5×10^-7m
- Distance of the screen from the slits (D) = 1m
To find:
The distance between the third dark fringe and the fifth bright fringe on the same side of the central maximum.
Solution:
1. Finding the distance between adjacent fringes:
The distance between adjacent bright and dark fringes can be given by the formula:
D = λD / d
Where, D is the distance between adjacent fringes.
Substituting the given values, we have:
D = (6.5×10^-7m x 1m) / (0.001m)
= 6.5×10^-4m
2. Finding the distance between the third dark fringe and the fifth bright fringe:
The distance between the third dark fringe and the fifth bright fringe can be calculated by using the formula:
Distance = (n + 1/2) x D
Where, n is the number of fringes.
For the third dark fringe, n = 3 and for the fifth bright fringe, n = 5.
Substituting the values in the formula, we get:
Distance = (3 + 1/2) x 6.5×10^-4m
= (7/2) x 6.5×10^-4m
= 3.25×10^-3m
= 3.25mm
Therefore, the distance between the third dark fringe and the fifth bright fringe on the same side of the central maximum is 3.25mm.
So, the correct option is 3) 3.25mm.