We’ll be back to your regularly-scheduled Physics Ninja series in a post or two. I’m taking this post to explain:
I) my recent blogging hiatus
II) the photoelectric effect
III) the parallels between the two
As much as I wish my radio silence was due to something unusual and awesome, like an internship with the Mythbusters or a thorough survey of the nation’s water parks, the actual cause is much more mundane:
I’ve been working. Seven days a week. At the moment I’m juggling two part-time jobs, which are taking up at least as much time and energy as one full-time job. My schedule isn’t concentrated into the standard Monday-Friday 9-5, and the oddly-timed breaks I have aren’t conducive to blogging. I don’t really write posts piecemeal; I need a fair amount of energy and a solid block of time in front of my monitor to push something through.
Because I’m a giant nerd, this reminds me of the photoelectric effect. The basic idea is that you can eject electrons (the “electric” part of the effect) from some metal surfaces by shining light (the “photo” part of the effect) on them. Light, like all electromagnetic waves, has a frequency that is related to how much energy it transmits. Different colors of light have different frequencies and therefore transmit different amounts of energy. The higher the frequency a wave has, the more energy it transmits. If light behaved purely like a wave, any color of light could achieve the photoelectric effect. All you would have to do is increase the intensity of the light, like turning up a dimmer switch. More intense light would mean more waves. More waves would mean more transmitted energy. Eventually the electrons would absorb enough energy to get ejected from the surface, right?
Except that’s not what happens. Light below a certain threshold frequency will not eject the electrons, regardless of intensity. When dealing with the photoelectric effect, light acts as a particle instead of a wave. Each light-particle, or photon, collides with an electron. All of the photon’s energy transfers to the electron; if this is enough energy to unstick the electron from the surface, the electron is ejected and the photoelectric effect is observed. If the frequency of the light is too low, an individual photon won’t have enough energy to eject an electron. Increasing the intensity doesn’t help. It wouldn’t matter how many of these low-energy photons collided with an electron. You can shoot a thousand BB’s at a boulder, but it’s still not going to go anywhere.
My writing style is more particle-like than wave-like. A few hours spread out over a couple days won’t enable me to write something substantial, while the same amount of time in a single night will. I metaphorically collided with a high-energy photon tonight, resulting in this post. Since one of my jobs is a tutoring gig, I’m hoping that the start of the school year should result in a more regular schedule. (During the summer, I could have students any time between 10AM and 8PM.) With any luck, I’ll begin posting with greater frequency (ha!) in the coming weeks.