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.  

Answered by Rafal K. Physics tutor

6215 Views

See similar Physics GCSE tutors

Related Physics GCSE answers

All answers ▸

A person swims from a depth of 0.50 m to a depth of 1.70 m below the surface of the sea. Density of the sea water = 1030 kg/m^3. Gravitational field strength = 9.8 N/kg. Calculate the increase in pressure on the swimmer. Give the unit.


What are the different kinds of nuclear radiation?


Compare the medical uses of ultrasound and X-rays. Your answer should include the risks, if any, and precautions, if any, associated with the use of ultrasound and X-rays. [6 marks]


Describe how a crumple zone on a car reduces injury to the driver in a crash.


We're here to help

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