In the photoelectric effect, why is the kinetic energy of the electrons independent of the intensity of light?

In our situation, the stopping potential doesn’t let any electron to pass. When we increase the frequency of incident light, the electrons get more energy. We know it from equation E=hf. When electrons gain more energy they can overcome the stopping potential. In effect they can reach the point due to acquired Kinetic Energy. Intensity doesn’t matter in this situation, because stopping potential will eventually force every additional electron back. Intensity just makes more electrons. On the other hand, higher energy caused by greater frequency makes current decrease. Constant intensity causes electrons to be ejected at the same rate all the time. They have greater velocity thanks to frequency. There will be fewer electrons travelling because they will quickly reach the point and there will be a time gap until the others will come. The experiment setup is like a motorway and current measured is like traffic. When there are few fast vehicles, there is no traffic.  

RK
Answered by Rafal K. Physics tutor

9449 Views

See similar Physics GCSE tutors

Related Physics GCSE answers

All answers ▸

If Hannah slows down from a speed of 12 m/s to 8 m/s and has a mass of 45kg, how much force has been exerted on her to cause this deceleration?


David left his basketball outside overnight. At 1am the volume of air within the ball was 1.2m^3 and the outdoor temperature was 5 degrees Celsius. At 3am the temperature was -7 degrees Celsius. What is the volume of air inside the ball at 3am?


What is the wavelength of a wave?


A car horn has a frequency of 680 Hz and a wavelength of 50cm. Calculate the speed of the sound waves produced by the car horn:


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2026 by IXL Learning