In a Young’s double slit experiment with slit separation 0.1 mm, one observes a bright fringe at angle ${1 \over {40}}$ by using light of wavelength $\lambda$ 1. When the light of wavelength $\lambda$ 2 is used a bright fringe is seen at the same angle in the same set up. Given that $\lambda$ 1 and $\lambda$ 2 are in visible range (380 nm to 740 nm), their values are -