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In photoelectric effect the graph of stopping potential (V₀) versus frequency (u) is a straight line. The slope of this graph is ________.

Asked in GUJCET 2026 · Stopping potential and kinetic energy graphs

Answer: (4) h/e

Step-by-step solution

Idea: Einstein's photoelectric equation, written with the stopping potential, is eV₀ = h u - φ₀.

Divide throughout by e: V₀ = (h/e) u - (φ₀)/e.

That is the form y = mx + c with y = V₀ and x = u, so the slope is h/e and the intercept carries the work function.

Notice the slope contains no property of the metal: every metal gives a line of the same slope h/e, about 4.14×10⁻¹⁵ V s, and only the intercept shifts.

So the slope of this graph is h/e.

Why the other options are wrong

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