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Physics · 2025 · 3 marks
Dual Nature of Radiation and MatterEinstein’s Photoelectric Equation: Energy Quantum of Radiation3 marksApplyshort answer
CBSE 2025 · Region 7 · Set 1 · Q26
(a) Define 'work function' of a metal. How can its value be determined from a graph between stopping potential and frequency of the incident…
(a)
Define 'work function' of a metal. How can its value be determined from a graph between stopping potential and frequency of the incident radiation?
(b)
The work function of a metal is $\displaystyle 2 \cdot 4 \mathrm{eV}$. A stopping potential of $\displaystyle 0.6$ V is required to reduce the photocurrent to zero, in a photoelectric experiment. Calculate the wavelength of light used.
Marking-scheme solution
(a)
Defining work function \(\displaystyle \frac{1}{2}\) Determining the value of work function from graph $\displaystyle 1$ (b)
Minimum energy required by an electron to escape from metal surface.
The intercept on the y axis for a graph between stopping potential & frequency gives \(\displaystyle \frac{\phi_{0}}{e}\).
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