Physics 9702 · AS & A Level · Photoelectric effect

Photoelectric effect — practice question

(a)[2]

Give two brief phenomena linked to the photoelectric effect that wave theory of light cannot account for.

(b(i))[1]

The maximum energy $E_{\text{MAX}}$ of electrons emitted from a metal surface when it is illuminated by light of wavelength $\lambda$ is described by $E_{\text{MAX}} = hc\left(\frac{1}{\lambda} - \frac{1}{\lambda_0}\right)$, where $h$ is the Planck constant and $c$ is the speed of light. Identify the symbol $\lambda_0$.

(b(ii)-1)[1]

Fig. 10.1 shows how $E_{\text{MAX}}$ varies with $\frac{1}{\lambda}$ for the metal surface. Use Fig. 10.1 to find the size of $\lambda_0$.

(b(ii)-2)[3]

Use the gradient of Fig. 10.1 to find the Planck constant $h$.

(c)[2]

The metal surface in (b) is oxidised. Photoelectric emission is still seen, but the work function energy is greater. On Fig. 10.1, draw a line that shows how $E_{\text{MAX}}$ varies with $\frac{1}{\lambda}$ for the oxidised surface.

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This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: Any two valid photoelectric-effect observations

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