[填空题]
Light is incident on a diffraction grating wit(zmc70pnghj (z/ 1s b:x 7foh/quoj n.rg(bzrcq/rfp03 0bl 5h and the pattern is viewed on a screen 2.5 m from the grating. The incident light beam consists of two wavelec(r5b p/q r 00rgfzlb3ngths, $\lambda_1\;=\; 4.6\times10^{ -7}\;m$ and $\lambda_2\;=\; 6.5\times10^{ -7}\;m$. Calculate the linear distance between the first-order bright fringes of these two wavelengths on the screen. m
