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Calculate the threshold wavelength (λ) for a material with a work function W = 6.2 eV.

1. Threshold wavelength (λ) = 2000 × 10⁻¹⁰ m
2. Threshold wavelength (λ) = 3000 × 10⁻¹⁰ m
3. Threshold wavelength (λ) = 4000 × 10⁻¹⁰ m
4. Threshold wavelength (λ) = 5000 × 10⁻¹⁰ m

Correct answer: Threshold wavelength (λ) = 3000 × 10⁻¹⁰ m

Solution

The threshold wavelength is calculated using the formula λ = hc/W, where h = 6.63 × 10⁻³⁴ J·s, c = 3 × 10⁸ m/s, and W = 6.2 eV = 6.2 × 1.6 × 10⁻¹⁹ J. Substituting these values gives λ ≈ 3000 × 10⁻¹⁰ m.

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