Green light of a certain wavelength is incident upon two valors separated by 2.10 x 10^-5 m. A screen is placed. 800m from the slits. The distance from the central bright line to the first-order line is 19.9 mm. What's the wavelength of the light?

for bright fringe on a young double slit u would use the formula

Y = (m * wavelength * distance from the screen) / (distance btn the slits)

Explanation:

since u already have distance btn the slits which is = 2.10 ... u have Y = 19.9 (u will change it to meters) u have distance from the screen is 800