---
title: "Students are investigating the photoelectric effect by shining monochromatic light from an adjustable source onto a metal plate, labeled Metal A. Metal A has a known work function \\(\\phi_A\\). The students use a detector circuit to determine the maximum kinetic energy \\(K_{\\text{max}}\\) of the electrons ejected from the plate for various frequencies \\(f\\) of the incident light."
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url: "https://nerd-notes.com/ubq/117694/"
date_modified: "2026-08-04T07:53:24+00:00"
---

# Students are investigating the photoelectric effect by shining monochromatic light from an adjustable source onto a metal plate, labeled Metal A. Metal A has a known work function \(\phi_A\). The students use a detector circuit to determine the maximum kinetic energy \(K_{\text{max}}\) of the electrons ejected from the plate for various frequencies \(f\) of the incident light.

Students are investigating the photoelectric effect by shining monochromatic light from an adjustable source onto a metal plate, labeled Metal A. Metal A has a known work function \(\phi_A\). The students use a detector circuit to determine the maximum kinetic energy \(K_{\text{max}}\) of the electrons ejected from the plate for various frequencies \(f\) of the incident light.

**Part a)** On the blank axes provided, **sketch** a graph of the maximum kinetic energy \(K_{\text{max}}\) of the ejected electrons as a function of the incident light frequency \(f\). **Label** the horizontal intercept as \(f_0\). *(2 points)*

**Part b)** **Explain** why the horizontal intercept \(f_0\) represents the threshold frequency for Metal A, using the principles of energy conservation and the photon model of light. *(2 points)*

**Part c)** The students set the light source to a specific frequency \(f = 2f_0\). On the blank grid provided, **draw** a bar chart to represent the energy of the incident photon \(E_{\text{photon}}\), the work function \(\phi_A\), and the maximum kinetic energy \(K_{\text{max}}\) of the ejected electron. The heights of the bars should correctly represent the relative magnitudes of these quantities. *(2 points)*

**Part d)** The students replace Metal A with Metal B, which has a work function \(\phi_B = 2\phi_A\). On the axes provided in part (a), **sketch** a second line representing \(K_{\text{max}}\) as a function of \(f\) for Metal B. **Label** this line 'Metal B'. **Justify** the slope and horizontal intercept of your new line compared to the line for Metal A. *(4 points)*


*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/117694/*