As red light shines on a piece of metal, no electrons are released. When the red light is slowly changed to shorter-wavelength light (basically progressing through the rainbow), nothing happens until yellow light shines on the metal, at which point electrons are released from the metal.
If this metal is replaced with a metal having a higher work function, which light would have the best chance of releasing electrons from the metal?
Red.
Blue.
Yellow would still work fine.
We need to know more about the metals involved.

Question

As red light shines on a piece of metal, no electrons are released. When the red light is slowly changed to shorter-wavelength light (basically progressing through the rainbow), nothing happens until yellow light shines on the metal, at which point electrons are released from the metal.
If this metal is replaced with a metal having a higher work function, which light would have the best chance of releasing electrons from the metal?
	 Red.
	 Blue.
	 Yellow would still work fine.
	 We need to know more about the metals involved.

anonymous · Answer

any clue? 
why do you think you had to wait till yellow light?? why the lights before that (longer wavelength light.. or lower frequency light) didn't work?

anonymous · Answer

the metal was glowing red at first then it slowly disappeared, I wasnt able to catch if it turns yellow either. but the flame of the torch was blue

anonymous · Answer

I dont understand what the question is asking. how would electrons be released if the first one didnt let electrons go

anonymous · Answer

and they are both metals so how do we know

anonymous · Answer

wait.. u did this experiment? ?

anonymous · Answer

no the professor did it during class with a metal stick and a torch looking thing

anonymous · Answer

but he only did it with one not two ?

anonymous · Answer

ok forget that.. 
did you learn about photoelectric effect yet? .. and if yes.. do you knwo waht work function is?
and also what threshold frequency is ?

anonymous · Answer

is that the same as photons? we covered slightly over it but no in depth

anonymous · Answer

well if it is the same stuff, we learned that is intensity is the same, frequency increases, and KE max also increases

anonymous · Answer

well.. photons are the particles of light.. 
and you have to learn, what characteristic of light determine the photoelectric effect..

anonymous · Answer

and unless you understand how photoelectirc effect works
and why classical theory DOESN"T work.. thats the beauty of this.. photoelectric efffect is a nightmare for the classical wave theory

anonymous · Answer

oh i dont think we got there yet

anonymous · Answer

Would the answer to this be red, I am assuming because blue is the hottest then is yellow and red it last

anonymous · Answer

or would it be the other way around red yellow and blue so it would be yellow

anonymous · Answer

No no.. the reasoning is not right.. i say wait until he covers the Einstiens photoelectri equation..(for which he was awarded the noble prize).. and then u come back to this.. and see if it makes sense!!

anonymous · Answer

yeah but its due tomorrow night lol I dont have class till monday =( I hate when they dont cover things and expect us to know it

anonymous · Answer

ok.. then ll kinda give you a crash course.. 

to remove electrons.. photons need to have enough energy.. how much energy?? that depends on what is called 'the work function'

a metal with higher work function => photons need more energy to strip off electrons


ok now what decides the energy of the photon? their frequency

red has least frequency .. ergo.. red photons have low energy
blue has high frequency ergo .. blue photons have AWESOME energy

so now you understand.. why your metal.. didn't shoot electrons until you shun yellow light.. that means.. the min energy required (the work function) for that metal.. was that of the energy of yellow photon


now.. the question is.. what if a metal has EVEN HIGHER work function.. 
waht do yo think.. ? which light can strip of electrons ?

anonymous · Answer

is it blue because blue has the highest amount of energy to strip off electron?

anonymous · Answer

exactly 
yellow cannot.. cause it could barely do it for the previous metal.

red DEFINITELY cannot.. hopeless
so blue is right.. !!! good job!

anonymous · Answer

thank you very much

anonymous · Answer

your welcome.. 

but u ll learn this in great detail.. and its really interesting.. the history behind it.. 
its amazing.. plz do learn how classical theory couldn't explain .. and it was a NIGHTMARE for physicist of that time.. absolute NIGHTMARE.. 
It was the genius of Karl Max Planck .. who had the guts to completely throw away the current theory and boldly come up with something REVOLUTIONARY .. in what he had said and i quote "an act of despair"..  He changed our lives.. !!

anonymous · Answer

oh i love physics ;P!!

anonymous · Answer

I see that =D I will definetly  go through it more but haven't been able to yet so I will, thanks for explaining all that, it did make sense once you told me about it, I will be excited to learn more about this coming week =D

anonymous · Answer

hehe great :D