Calculating Distance Between Second-Order Fringes of Different Wavelengths

Explanation:

When 760-nm and 640-nm light pass through two slits 0.68 mm apart, the distance between the second-order fringes can be calculated using the formula:

d * theta = 2 * (lambda₁ - lambda₂)

Given that the distance between the slits (d) is 0.68 mm, the angle of diffraction (theta) is approximately 20 degrees, and the wavelengths of light are 760 nm and 640 nm, we can plug the values into the formula:

0.68 mm * 20 degrees = 2 * (760 nm - 640 nm) = 0.33 mm

Therefore, the distance between the second-order fringes for these two wavelengths is 0.33 mm.