Photoelectric Bench

Wavelength λ

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Photon energy hf

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Photon rate N

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E_{k max}

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Stopping voltage V₀

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Current I

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Current I vs anode voltage V

Frequency f

f₀

3.5visibleUV →30 ×10¹⁴ Hz

Beam power P

Hold P constant while sweeping f (photon rate falls as 1/f)

Anode voltage V

−8 V · retarding0+8 V · accelerating

Target metal

h = 6.63 × 10⁻³⁴ J s. At constant P, raising f lowers the photon arrival rate N = P/hf — the current falls even above threshold.