Negative Work function in Photo electric effect

[logearav]

Homework Statement

In my attachment, the x intercept gives threshold frequency and the y intercept gives the work function.

Homework Equations

The Attempt at a Solution

Work function is the minimum energy needed to pull out an electron from the metal surface. My question is, from the graph, work function is a negative value. Will work function takes negative values?

 

[Doc Al]

In my attachment, the x intercept gives threshold frequency and the y intercept gives the work function.

The y intercept gives the negative of the work function. (It's even marked -Φ on the diagram.) The work function is positive.

 

[logearav]

Doc Al,
How negative of the work function becomes positive work function.

 

[Doc Al]

Doc Al,
How negative of the work function becomes positive work function.

The work function is the negative of the y-intercept. Since the y-intercept is negative, the work function is positive.

 

[logearav]

I got it now Doc Al. Thank you so much