Two different metals A and B are illuminated by the same monochromatic radiation of wavelength 300 nm. Their measured stopping potentials are 2.0 V and 0.5 V respectively. Which statement about their work functions is correct?
Options

Question

Two different metals A and B are illuminated by the same monochromatic radiation of wavelength 300 nm. Their measured stopping potentials are 2.0 V and 0.5 V respectively. Which statement about their work functions is correct?

Options

G1 Physics · Accepted Answer

For the same incident photon energy, eV₀ = hν−φ. Therefore, φ = hν−eV₀. A larger stopping potential means a larger maximum kinetic energy and therefore a smaller work function. Thus metal B, which has the smaller stopping potential, has the larger work function. The difference is φ(B)−φ(A) = e[V₀(A)−V₀(B)]. In electron-volt units: φ(B)−φ(A) = 2.0−0.5 = 1.5 eV. Correct option: B.