What is the charge of an electron and the nature of stopping potential?

[blooperkin]

For this post, I'll be mainly referring to this photoelectric equation:

Fig 1: Photoelectric equation

1) Is 'e' the charge of an electron, ie. a negative value? Or just an elementary charge, ie. a positive value?

2) Is stopping potential (Vs) a positive or negative value? Because in my lecture notes, there's two different graphs, one saying that Vs is positive, and one saying that it's negative:

Fig 2: Current against Potential difference graph

Fig 3: Stopping potential vs Frequency graph

2) Googling 'stopping potential vs frequency graph' yields me almost similar results of this graph:

Fig 4: Stopping potential vs Frequency graph

Must threshold frequency necessarily be the x intercept? Can it be any higher value, like the one shown in Fig 3?

Thanks!

 

[mfb]

1) Is 'e' the charge of an electron, ie. a negative value? Or just an elementary charge, ie. a positive value?

Hmm... it looks like an elementary charge, but that does not fit to the sketch later. Let's say it is the charge of an electron.

2) Is stopping potential (Vs) a positive or negative value?

You can choose that in the experiment. The voltage where the current goes to zero is always "stopping" (the object where the light hits has a higher electric potential).

Must threshold frequency necessarily be the x intercept?

Yes. That is the minimal frequency where you get electrons out of the material.

 

[bhavana goud]

As the terminals attached to the battery are changed for stopping the emission of electrons, after few minutes galvonometer stops deflecting and reaches to zero . Even though light rays are incident on photographic plate electron emission stops and thus stopping potential remains constant .

 

[bhavana goud]

For stopping potential, photographic plate should be attached with positive terminal so that electrons emitted does not move towards collector . Electric current and stopping potential becomes zero