[填空题]
Light is incident on a dli-9r n jiwi9xw ctn)-6c-3 p*txp-kdiffrack q v)cm:0sw/a. lp3+p gv2qvgw 17lxkf6ex -ztion grating with and the pattern is viewed on a screen 2.5 m from the grati/6xs.gmwq7x2 3 ppvea:)kv lg l0fwk 1zv c+q-ng. The incident light beam consists of two wavelengths, $\lambda_1\;=\; 4.6\times10^{ -7}\;m$ 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
