>>11039296>>>11039273 (You) #For the 100th time:
Why is there a threshold wavelength for light-induced electron emission in zinc? How much more precise can I be? If I had to write an exercise for an exam, I would ask you to describe what is shown in this plot. I'd give you half a point for describing what's on the axes, half a point for "zero, then at some point linear" and 2 points for the subsequent explanation. Half a bonus point if you describe the point where the linear part would meet the y axis. So if you want this to be exam-like, I ask you to answer this as if it was an exam question.
>But I already answered where the minimum comes from, it's because you need to stimulate the element with enough energy to move the electrons fast enough that they leave the surface of the element.My answer is
The electrons on the surface of the zinc are bound to the nucleus by electronegativity, this binding force needs to be overcome for the electrons to reach escape velocity, so below a certain threshold the electrons remain bound to the zinc atom.
To explain the red versus blue light phenomenon I will use this analogy.
If you have a blowtorch with a low heat setting, creating a big yellow flame, and a high heat setting, with a small blue flame,
With the same amount of gas (energy) dueling the flame, it will be impossible to get the low heat setting to make a metal rod glow, but with the high setting you will be able to make the metal rod glow and begin emitting electrons,
So a low energy red light source with the same power as a high energy blue light source will never be able to cause electron emission in the same way.
Another way to imagine it is with low frequency bass versus high frequency treble, if you put 100 watts of power into a big subwoofer and play 50 hertz, versus 100 watts into a small tweeter and play 25000 hertz, the low frequency will be only moderately loud, say 80 decibels, while the tweeter will reach approx 140 decibels.
