How Does the Photoelectric Effect Relate to Electron Kinetic Energy?

[kabtq9s]

Hello,

This question is based on the passage to the left.
Please I need some one to explain it to me in "baby steps" if possible. I already read another explanation of it .. (posted below the picture) but i still can't understand how the final kinetic energy will be the same as the initial potential energy

especially since the explanation of a smiliar problem on this exams states that "The charged electron particles accelerate in an electric field. The electron starts with a velocity that increases as it approaches the anode through the vacuum. "

The other explanation: An electron is negatively charged, so it will accelerate from the negatively charged cathode to the positively charged anode. From energy standpoint, this is equivalent to the electron's potential energy being converted to the kinetic energy. If the energy of the photon that is used to eject the electron is only slightly larger than the electron's work function, then the electron has very little kinetic energy. In other words, its initial kinetic energy is approximately 0. When the electron reaches the anode, approximately all of its final kinetic energy is from the initial potential energy. Hence they are equal.

 

[Drakkith]

but i still can't understand how the final kinetic energy will be the same as the initial potential energy

What don't you understand about it? The explanation pretty much says it all. Do you understand potential energy?

 

[kabtq9s]

What don't you understand about it? The explanation pretty much says it all. Do you understand potential energy?

The question asks to compare the final kinetic energy to the initial potential energy. I imagine the electron as a ball on top of a waterfall. At the top of the waterfall it's potential energy will be at max, and when it finally falls and reaches the bottom of the waterfall its kinetic energy will be at 0 . So how can the potential energy equal the kinetic energy in this case.

Thanks in advance

 

[SpectraCat]

The question asks to compare the final kinetic energy to the initial potential energy. I imagine the electron as a ball on top of a waterfall. At the top of the waterfall it's potential energy will be at max, and when it finally falls and reaches the bottom of the waterfall its kinetic energy will be at 0 . So how can the potential energy equal the kinetic energy in this case.

Thanks in advance

You are supposed to consider the instant right before it hits, while it is still in free-fall, but has traveled the full height of the waterfall. At that instant, all of the gravitational potential energy the ball had when it was at the top of the waterfall has been converted into kinetic energy, so the two quantities are equal.

 

[kabtq9s]

You are supposed to consider the instant right before it hits, while it is still in free-fall, but has traveled the full height of the waterfall. At that instant, all of the gravitational potential energy the ball had when it was at the top of the waterfall has been converted into kinetic energy, so the two quantities are equal.

Ok that makes sense, thank you. But does the explanation in blue say the same thing? it looks more complicated, also where does the 50V fit in our explanation ?

Thanks in advance

Edit: Never mind, I think I understand now. The 50v is the potential difference between the electrons that will drive the kinetic energy