Photoelectric Effect: Measuring Stopping Voltage

[tomz]

Hi everyone, a quick question on photoelectric effect.

Why measure stopping voltage by connecting a battery to the circuit and then adjust until current reach 0? Cant we just use a voltmeter?


Thank you!

 

[mfb]

In theory, you could wait until all the photo-electrons generate the voltage themself - but that would require so many photo-electrons that it is not practical. In addition, no isolation is perfect (especially with an attached voltmeter), the system would discharge itself.

 

[tomz]

In theory, you could wait until all the photo-electrons generate the voltage themself - but that would require so many photo-electrons that it is not practical. In addition, no isolation is perfect (especially with an attached voltmeter), the system would discharge itself.

Thanks. After some thinking I guess there is also the problem that not all electrons released have the theoretical maximum energy, so the potential get from a voltmeter will be biased

 

[sophiecentaur]

Thanks. After some thinking I guess there is also the problem that not all electrons released have the theoretical maximum energy, so the potential get from a voltmeter will be biased

The distribution in velocities will just mean that it takes longer to reach the maximum voltage - the low velocity electrons will play no part in the process once the voltage is greater than their particular stopping voltage.
Finding the value of V that will stop the current would be a more practical way, I think - which is why it's recommended.

 

[sardar]

I can explain the reasoning behind measuring stopping voltage in the photoelectric effect by connecting a battery to the circuit and adjusting until the current reaches 0. The photoelectric effect is a phenomenon where electrons are emitted from a material when light of a certain frequency is shone on it. These emitted electrons have a certain amount of kinetic energy, which can be measured by the stopping voltage. By connecting a battery to the circuit, we can adjust the voltage until it is equal to the kinetic energy of the emitted electrons, causing the current to reach 0. This allows us to accurately measure the stopping voltage and understand the relationship between the frequency of light and the energy of the emitted electrons. Using a voltmeter alone would not give us this information and may not accurately measure the stopping voltage. Therefore, connecting a battery and adjusting the voltage is a more precise method of measuring the stopping voltage in the photoelectric effect.