By using Einstein photoelectric equation, if we consider kinetic energy of photo electrons on y-axis and frequency of incident radiation on x-axis. The slope of the graph will represent (the symbols have their usual meanings)
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \( h \)
Einstein’s photoelectric equation gives the maximum kinetic energy of the photoelectrons as a linear function of the frequency, and a straight line has the form \( y = mx + c \).
\( K_{\max} = h\nu - \Phi_0 \)
With \( K_{\max} \) on the y-axis and \( \nu \) on the x-axis, the slope is the coefficient of \( \nu \), that is Planck’s constant h, and the intercept on the y-axis is \( -\Phi_0 \). The graph meets the x-axis at the threshold frequency \( \nu_0 = \Phi_0/h \).
NCERT (2026-27):
Einstein’s Photoelectric Equation: Energy Quantum of Radiation – “… If this quantum of energy absorbed exceeds the minimum energy needed for the electron to escape from the metal surface (work function φ0), the electron is emitted with maximum kinetic energy
\( \displaystyle K_{max} = h\nu - \phi_0 \qquad (11.2) \)”
Einstein’s Photoelectric Equation: Energy Quantum of Radiation – “… According to Eq. (11.2), Kmax depends linearly on ν, and is independent of intensity of radiation, in agreement with observation.”