The light of wavelength $\lambda$ is incident on the surface of a metal with work function $\phi$ and emits electrons. What is the maximum velocity of the emitted electrons? [Given: $m=$ mass of electron,$h=$ Planck's constant,$c=$ velocity of light]

• A
  $\left[\frac{2(hc-\lambda)}{m \lambda}\right]^{\frac{1}{2}}$
• B
  $\left[\frac{2(hc-\phi) \lambda}{mc}\right]^{\frac{1}{2}}$
• C
  $\left[\frac{2(hc-\lambda)}{m \lambda}\right]$
• D
  $\left[\frac{2(hc-\phi \lambda)}{m \lambda}\right]^{\frac{1}{2}}$