Two sources of light of wavelength 4500 Å annd 6000 Å are used simultaneously in Young's double slit experiment. At which order of the two wavelength pattern,s the fringes coincide?

Options

A. 3rd orders of both `lamda_(1) and lamda_(2)`
B. 4th orders of both `lamda_(1) and lamda_(2)`
C. 4th order of `lamda_(1)=4500` Å and 3rd order of `lamda_(2)=6000` Å
D. 3rd order of `lamda_(1)=4500` Å and 4th order of `lamda_(2)=`6000 Å

Answer

C

Explanation

At a given point `nlamda=`constant
`therefore n_(1)lamda_(1)=n_(2)lamda_(2)" "therefore (n_(1))/(n_(2))=(lamda_(2))/(lamda_(1))=(6000)/(4500)=(4)/(3)`
`therefore 4xx4500=3xx6000`