The following readings were obtained in a laboratory study of the photo-electric…
PHYSICS · Multi-part · A Level · Physics · Particles and radiation · Particles and radiation
Problem
The following readings were obtained in a laboratory study of the photo-electric effect from a clean metal surface.
Frequency of incident light (in 1014Hz): 5.5, 6.0, 6.5
Corresponding stopping potential (in V): 0.4, 1.2, 2.0
Answer the following.
(i) Draw a graph of the stopping potential V0 (vertical axis) against frequency ν (horizontal axis) using the above data. Extend your straight line to meet both axes.
(ii) Using suitable points from your graph, find the numerical value of the slope and intercept. Hence determine the value of Planck’s constant h (take elementary charge e=1.6×10−19C).
(iii) From the intercept on the frequency axis, calculate the threshold wavelength for this metal.
(iv) Using your value of h, find the maximum speed of the emitted electrons when light of frequency 7.0×1014Hz is incident on the same surface. (Electron mass me=9.1×10−31kg.)