A silver sphere (work function 4.6 eV) is suspended in a vacuum chamber by an insulating thread. Ultraviolet light of wavelength 0.2 μm strikes on the sphere. The maximum electric potential of the sphere will be (hc = 12400 eV·Å):
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Question

A silver sphere (work function 4.6 eV) is suspended in a vacuum chamber by an insulating thread. Ultraviolet light of wavelength 0.2 μm strikes on the sphere. The maximum electric potential of the sphere will be (hc = 12400 eV·Å):

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G1 Physics · Accepted Answer

Step 1: Photon energy is Eγ = hc/λ and Einstein's equation is Kₘₐₓ = Eγ−φ. Step 2: If a stopping potential is involved, Kₘₐₓ = eVₛ. Step 3: Using the two stated cases eliminates φ or gives it directly. Final: C: 1.6 V.