In the photoelectric effect, what happens as you increase the frequency of light keeping the same intensity constant?

E=hf, so as you increase the frequency of light, the energy of each photon hitting the metal surface is greater. Thus the electrons liberated from the surface of the metal have a greater maximum kinetic energy.
We also said that the intensity of the light should stay the same. Intensity = Power/Area = (Energy/time)/Area. Given that the energy of each photon is greater with a higher frequency of light, there must be fewer photons hitting the metal surface per unit time in order to keep the intensity constant.
Thus, assuming that initially the photon frequency was above the threshold frequency, increasing the frequency at the same intensity will increase the kinetic energy of the photoelectrons liberated from the metal surface, but also reduce the number of electrons released.

Answered by Alexander J. Physics tutor

20777 Views

See similar Physics A Level tutors

Related Physics A Level answers

All answers ▸

Show that a pendulum undergoes simple harmonic motion (SHM). State your assumptions. The pendulum is made up of a light inextensible string, attached to a ceiling at one end and with a particle of mass m attached to the other end.


Using Newton's law of universal gravitation, show that T^2 is proportional to r^3 (where T is the orbital period of a planet around a star, and r is the distance between them).


Is the excitation and de-excitation of an electron from the ground state (of an atom) due to the collision of another particle (e.g. electron) an elastic collision or an inelastic collision.


This is a question on the photoelectric effect: For potassium, the work function is 3.65E-19J. Find the maximum wavelength of light that will cause photoelectrons to be emitted when shone onto potassium.


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences