|
In a rush? A summary of the photoelectric effect, useful for review otherwise read on |
|
On the back of Planck's attempt to reconcile classical physics and blackbody radiation , and the anomalous observations from Philip Lenard, Einstein came up with a radical explanation for light and in doing so ushered in the idea of the wave-particle duality of light
An analogy
Whether you are a teacher, or student, this analogy-story maybe useful to appreciate what the Photoelectric Effect is
Whether you are a teacher, or student, this analogy-story maybe useful to appreciate what the Photoelectric Effect is
|
Mr Looyen, a physics teacher, stands in front of the classroom full of students. The bell goes.
“Hey, I know you don't want to leave my classroom, heck, I know you love physics, but the bell has gone, you really have to go.”, he says A student pipes up, “only if you pay us, sir?’ Initially perplexed, he responds, “alright, how much?” “Well, we want $6 and we won’t take any less" comes the reply" "...and we won’t give change either!” says another. Mr Looyen pulls out a wad of $5 bills and starts handing them out. They accept them, but much to the teachers annoyance, they refuse to move. He says, “ I know that's not $6, but surely you can pool them so some of you can leave.” |
“Nah,” comes the reply, “ "its $6 minimum each so don't short change us. We''ll take you $5 but it won't make us leave!
Mr Looyen shrugs his shoulders and sighs, and proceeds to take out a wad of $10 bills. The students smile. As he hands out the $10 bills, one to each student, the students start to leave, muttering that they have $4 to spend at the canteen. Packing up, a little poorer, he readies to leave the classroom , but as he looks up, he sees a group of students still sitting in their chairs. Perplexed, he says “hey, why are you still here? One of the remaining students reply, “well, you see…. our minimum requirement is $11!! |
Sample Problem
We are now ready to try a sample problem
Below is a sample problem with a video that explain how to solve it. It is suggested you try the problem beforehand, as this actually aids understanding, even if you are unsure if you are correct.
We are now ready to try a sample problem
Below is a sample problem with a video that explain how to solve it. It is suggested you try the problem beforehand, as this actually aids understanding, even if you are unsure if you are correct.
|
|
Extra videos
Two videos - one basic, one more detailed - done in collaboration with University of Sydney Kickstart and CrookED Science
Two videos - one basic, one more detailed - done in collaboration with University of Sydney Kickstart and CrookED Science
|
|
|
Addressing a misconception
When we say that intensity affects the amount of current, but not the energy, it is important to note that there is a caveat
This brief video addresses a common error when trying to understand the photoelectric effect and it has to do with the meaning of intensity
When we say that intensity affects the amount of current, but not the energy, it is important to note that there is a caveat
This brief video addresses a common error when trying to understand the photoelectric effect and it has to do with the meaning of intensity
Interactive
THis is a demonstrate of the set up (from pHET)
Some thing you could try
THis is a demonstrate of the set up (from pHET)
Some thing you could try
- Can you order the metals in terms of their work function?
- What are the threshold frequencies for selected metals?
- Can you calculate the maximum kinetic energy for various frequencies?
