---
title: "A monochromatic light beam illuminates a metal surface with work function \\(\\Phi\\) in an evacuated phototube. An experimenter records the stopping potential \\(V_s\\) required to reduce the photocurrent to zero as a function of the light intensity for two different light sources: one with frequency \\(f_1\\) where \\(hf_1 > \\Phi\\), and one with frequency \\(f_2\\) where \\(hf_2 < \\Phi\\). Which of the following best describes the graphs of stopping potential \\(V_s\\) as a function of light intensity for each frequency?"
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url: "https://nerd-notes.com/ubq/123478/"
date_modified: "2026-09-28T11:59:53+00:00"
---

# A monochromatic light beam illuminates a metal surface with work function \(\Phi\) in an evacuated phototube. An experimenter records the stopping potential \(V_s\) required to reduce the photocurrent to zero as a function of the light intensity for two different light sources: one with frequency \(f_1\) where \(hf_1 > \Phi\), and one with frequency \(f_2\) where \(hf_2 < \Phi\). Which of the following best describes the graphs of stopping potential \(V_s\) as a function of light intensity for each frequency?

A monochromatic light beam illuminates a metal surface with work function \(\Phi\) in an evacuated phototube. An experimenter records the stopping potential \(V_s\) required to reduce the photocurrent to zero as a function of the light intensity for two different light sources: one with frequency \(f_1\) where \(hf_1 > \Phi\), and one with frequency \(f_2\) where \(hf_2 < \Phi\). Which of the following best describes the graphs of stopping potential \(V_s\) as a function of light intensity for each frequency?

- **A.** For \(f_1\), \(V_s\) increases linearly with intensity; for \(f_2\), \(V_s\) remains constant at zero for all intensities.
- **B.** For \(f_1\), \(V_s\) remains constant at a positive non-zero value for all intensities; for \(f_2\), \(V_s\) remains constant at zero for all intensities.
- **C.** For \(f_1\), \(V_s\) remains constant at a positive non-zero value for all intensities; for \(f_2\), \(V_s\) increases linearly with intensity once a threshold intensity is exceeded.
- **D.** For both \(f_1\) and \(f_2\), \(V_s\) increases linearly with intensity, with \(f_1\) producing a greater rate of increase than \(f_2\).

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123478/*