Q55 / 75 · JEE Main 2025 (3 Apr Shift 1) · Physics

The work function of a metal is 3 eV. The color of the visible light that is required to cause emission of photoelectrons is

  • A
    Green
  • Correct answer
    B
    Blue
  • C
    Red
  • D
    Yellow

Solution

$\begin{aligned}<br/>& (\mathrm{KE})_{\max }=\frac{\mathrm{hc}}{\lambda}-\phi \\ & \frac{\mathrm{hc}}{\lambda} \gt \phi[\text { for emission }] \\ & \lambda \lt \frac{\mathrm{hc}}{\phi} \Rightarrow \lambda \lt \frac{1242}{3} \mathrm{~nm}<br/>\end{aligned}$
So blue light option (B)

Hence, the correct answer is option: 'B'.

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