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In an experiment to calculate Planck's constant, light with varying wavelengths was shone on a metal surface, and the energy of the emitted photoelectrons was determined using stopping potentials. The following data was recorded for the wavelength (λ) of the light and the corresponding stopping potential (V₀): λ (μm) | V₀ (V) 0.3 | 2.0 0.4 | 1.0 0.5 | 0.4 Using c = 3 × 10⁸ m/s and e = 1.6 × 10⁻¹⁹ C, the value of Planck's constant (in J·s) obtained from this experiment is:

1. 6.0 × 10⁻³⁴
2. 6.4 × 10⁻³⁴
3. 6.6 × 10⁻³⁴
4. 6.8 × 10⁻³⁴

Correct answer: 6.4 × 10⁻³⁴

Solution

Using the photoelectric equation, h = eV₀λ/c, the data points are used to calculate Planck's constant. The average value obtained from the data is 6.4 × 10⁻³⁴ J·s.

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