Photoelectric Effect Demo

This is a demonstration of the photoelectric effect using an ultraviolet source, a zinc plate, a Braun electroscope, an ebonite rod, and fur. The zinc plate is place atop the electroscope and charged negatively by rubbing the rod with fur and touching the rod to the plate. The plate is then irradiated by ultraviolet light and quickly loses its charge, as measured by the electroscope, as UV photons eject electrons from the surface.

This demonstration was created at Utah State University by Professor Boyd F. Edwards, assisted by James Coburn (demonstration specialist), David Evans (videography), and Rebecca Whitney (closed captions), with support from Jan Sojka, Physics Department Head, and Robert Wagner, Executive Vice Provost and Dean of Academic and Instructional Services.

[nishantbansal]

thats what education system in schools needed

[artisticnoob]

I found what I was looking for! Not reading definations and stuff

[karunagarenjonathansamband]

very good explanation .Loves this video

[afro]

Eu estava esperanco um exploção, mas eu aprendi o que e o efeito fotoeletrico. Cool !!!!

[KickOutTheJhm]

Photoelectric sensors are also whats used in most modern day smoke detectors in residential and commercial/ industrial construction and renovation.

[safaesafae]

thank you so much that was incredibly useful

[sirisharepaka]

Wow this is super cool to understand thank you sir😊🙏

I would suggest to show also that a common lamp is not able to knock off electrons from the zinc no matter for how long or strong it shines. Only wavelength short enough will so it. Otherwise nice video thanks

[diegocolomes]

I'm not sure if I'm correct but I think the plate is not "negatively charged" but positively charged, since the rod was charged taken away electrons with the fur (so also positively charged). So the rod took away electrons from the plate.

[tonystark]

Hi sir if we pass the the threshold frequency through any electro magnetic field then what will be the result I tried solving and I got the equation as hVø^2=2hv`+k.Eø^2

[baharosman]

Did he explain it or performed the experiment?

[solank]

1:46 How to they know electrons are getting kicked off, rather than mixing with particles from the light and being turned neutral, or something else like that?

Have they done more complicated experiments where they use detectors elsewhere that detect where the electrons go?

[payalnarwal]

Indians are watching these videos more 😂

[blancaroca]

Nice demo. I study this in UK. Can I ask a question.
Why use zinc if it oxidizes? Most metals have similar work function values all around 4 eV.
Also is it absolutely necessary to pre-charge the plate? Can we not just let the photoelectons carry away negatives and leave a net positive which should also be observable on the electroscope? Thanks anyone.