[填空题]
Light of wavelength .lpc6/ sv.wc8vpnfbgr a7e9j ;:tg- z y.(wj)1(vujwt o25(xmcnl4 oe l lb-o $ 5.0\times10^{7 }\;m$ passes through two parallel slits and falls on a screen 4.0 m away. Adjacent bright bands of the interference pattern are 2.0 cm apart.
(a) Find the distance between the slits. mm
(b) The same two slits are next illuminated by light of a different wavelength, and the fifth-order minimum for this light occurs at the same point on the screen as the fourth-order minimum for the previous light. What is the wavelength of the second source of light? $\lambda_2$ $ \times10^{-7 }\;m$
