Students are studying the photoelectric effect using the apparatus shown in Figure 15.
Figure 16 shows the results the students obtained for the maximum kinetic energy
- Using only data from the graph, determine the values the students would have obtained for
-
- Planck's constant,
. Include a unit in your answer (2 marks)
- Planck's constant,
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-
- the maximum wavelength of light that would cause the emission of photoelectrons (1 mark)
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- the work function of the metal of the photocell. (1 mark)
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- The work function for the original metal used in the photocell is
.
On Figure 17, draw the line that would be obtained if a different metal, with a work function of, were used in the photocell. The original graph is shown as a dashed line. (2 marks)
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a. i.
ii.
iii.
b.
a.i. Planck’s constant
→ Equal to the gradient of the line when
a.ii. → Max wavelength = minimum frequency of emitted photoelectron.
a.iii.
→ The work function is the y-intercept of the graph, so by extending the graph as shown above, the work function is
b. → The new y-intercept for the graph will be
→ The gradient of the graph will remain the same (Planck’s constant)
