The disntances of poinnt on the screen from two slits are `1.8xx10^(-5)m and 1.23xx10^(-5)m`. If the wavelength of light used is 6000 Å, then the number of bright or dark band formed at that point is

Options

A. `9^(th)` dark dringe
B. `10^(th)` dark dringe
C. `10^(th)` bright fringe
D. `11^(th)` dark fringe

Answer

B

Explanation

Path diff. `=1.8xx10^(-5)-1.23xx 10^(-5)`
`=0.57xx10^(-5) m`
Now, `n=("Path diff")/("Wavelenght")`
`=(0.57x10^(-5))/(6xx10^(-7)) =9.5`
Thus, given points is `10^(th)` dark point.