The work function of a metal surface is $4\mathrm{.}80{10}^{-19}J.$ The maximum speed of the electrons emitted from the surface is $v_A=7\mathrm{.}1{10}^5\frac{m}{s}$ when the wavelength of the light is ${}_A.$ However, a maximum speed of $v_B=5\mathrm{.}7{10}^5\frac{m}{s}$ is observed when the wavelength is ${}_B.$ Find the wavelengths ${}_A$ and ${}_B.$

${}_A=$

${}_B=$

The work function of a metal surface is $4\mathrm{.}80{10}^{-19}J.$ The maximum speed of the electrons emitted from the surface is $v_A=7\mathrm{.}1{10}^5\frac{m}{s}$ when the wavelength of the light is ${}_A.$ However, a maximum speed of $v_B=5\mathrm{.}7{10}^5\frac{m}{s}$ is observed when the wavelength is ${}_B.$ Find the wavelengths ${}_A$ and ${}_B.$

${}_A=$

${}_B=$