# Photoelectric Effect questions to help my understanding

Jeff97
Homework Statement:: This isn't homework, I didn't know exactly where to post my question so I thought it would be safest to post here.
Relevant Equations:: N/a

My questions are as follows:

1. When the voltage is increased to a certain value the current between the two plates(emitter plate) is reduced to zero. Can someone explain to me why increasing the voltage can stop the current?

2. How did Bohr modify the Rutherford model to explain the stability of hydrogen and its spectrum.?

I was thinking it was because... The motion of the electrons in the Rutherfords model was unstable because, according to classical mechanics and electromagnetic theory, any charged particle moving on a curved path emits electromagnetic radiation; thus, the electrons would lose energy and spiral into the nucleus.

So to remedy the stability problem, Bohr modified the Rutherford model by requiring that the electrons move in orbits of fixed size and energy. The energy of an electron depends on the size of the orbit and is lower for smaller orbits. Radiation can occur only when the electron jumps from one orbit to another. The atom will be completely stable in the state with the smallest orbit, since there is no orbit of lower energy into which the electron can jump.?

Mentor
This isn't homework, I didn't know exactly where to post my question so I thought it would be safest to post here.
Thank you for defaulting to the Homework Help forums when you are not sure. But since these are general questions about the photoelectric effect, your thread has been moved to the technical forums.

I'm guessing that @ZapperZ will be able to help you with some intuition on this subject... • Jeff97
Staff Emeritus
Homework Statement:: This isn't homework, I didn't know exactly where to post my question so I thought it would be safest to post here.
Relevant Equations:: N/a

My questions are as follows:

1. When the voltage is increased to a certain value the current between the two plates(emitter plate) is reduced to zero. Can someone explain to me why increasing the voltage can stop the current?

This is a reverse-bias voltage, meaning the opposite plate has a lower potential than the photocathode (where the electrons came out of). As you increase the reverse bias, more and more electrons are being repelled away until at some point, even the most energetic electrons cannot reach that plate. So you get no current.

Zz.

• • berkeman and Jeff97
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