Photoelectric Effect: Measuring Stopping Voltage

Click For Summary

Discussion Overview

The discussion revolves around the methodology for measuring stopping voltage in the context of the photoelectric effect. Participants explore the practicality and implications of using a battery versus a voltmeter for this measurement.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions the necessity of using a battery to measure stopping voltage, suggesting that a voltmeter could suffice.
  • Another participant argues that relying solely on photo-electrons to generate the voltage would be impractical due to the need for a large number of electrons and the potential for system discharge when using a voltmeter.
  • A later reply reiterates the impracticality of relying on photo-electrons alone, noting that the energy distribution of emitted electrons means that not all will contribute to reaching the maximum voltage, leading to biased readings from a voltmeter.
  • Participants suggest that measuring the stopping voltage by adjusting the battery until the current reaches zero is a more practical method, as it accounts for the varying energies of the emitted electrons.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of using a voltmeter versus a battery for measuring stopping voltage, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

Participants highlight limitations related to the assumptions about electron energy distribution and the practical challenges of measurement techniques, but do not resolve these issues.

tomz
Messages
35
Reaction score
0
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!
 
Physics news on Phys.org
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.
 
mfb said:
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
 
tomz said:
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.
 

Similar threads

Undergrad Photoelectric effect and bound electrons
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Can infrared photons also eject electrons in 'photoelectric effect'?
  • · Replies 5 ·
Replies
5
Views
3K
Graduate Saturation voltage for photoelectric current
  • · Replies 16 ·
Replies
16
Views
3K
Graduate Photoelectric effect : retarding potential with back current
  • · Replies 1 ·
Replies
1
Views
4K
Undergrad Question about the Photoelectric Effect and the Work Function of a Metal
  • · Replies 5 ·
Replies
5
Views
2K
High School The voltage between two points
  • · Replies 11 ·
Replies
11
Views
2K
Undergrad Why is a potentiometer used in this circuit instead of a variable resistor?
  • · Replies 2 ·
Replies
2
Views
6K
Undergrad Potential difference between a battery's terminal and Earth ground
  • · Replies 58 ·
2
Replies
58
Views
6K
High School Voltage between the positive terminal of a battery and a point in the air
  • · Replies 5 ·
Replies
5
Views
2K
Undergrad Photoelectric effect: Saturation voltage
  • · Replies 4 ·
Replies
4
Views
2K