In a biprism experiment, if the 6th bright bannd with a wavelength `lamda_(1)` coincides with 7th dark band with a wavelength `lamda_(2)`, then the ratio of the wavelengths `((lamda_(1))/(lamda_(2)))` is

Options

A. `(12)/(13)`
B. `(13)/(12)`
C. `(6)/(7)`
D. `(7)/(6)`

Answer

B

Explanation

`6X=(6.5)X^(1)" "therefore (X)/(X^(1))=(6.5)/(6)=(13)/(12)`
but `X=(lamdaD)/(d) " "therefore Xprop lamda`
`therefore (lamda_(1))/(lamda_(2))=(13)/(12)`