A light beam is shining on a metal target that has a work function of 1.8 eV.If a stopping potential of 0.7 V is required,what is the wavelength of the incoming monochromatic light? (h = 6.63 × 10−³⁴ J⋅s,c = 3.00 × 10⁸ m/s,1 eV = 1.60 × 10−¹⁹ J,and 1 nm = 10−⁹ m) A)497 nm B)166 nm C)796 nm D)1130 nm E)691 nm

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Quizplus · Accepted Answer

The energy of the incoming light can be calculated using the photoelectric effect equation: $E = \phi + eV$, where $E$ is the energy of the incoming light, $\phi$ is the work function, and $V$ is the stopping potential. Substituting the given values, $E = 1.8\, \text{eV} + 0.7\, \text{eV} = 2.5\, \text{eV}$. Converting this energy to joules gives $E = 2.5 \times 1.60 \times 10^{-19}\, \text{J} = 4.0 \times 10^{-19}\, \text{J}$. The wavelength $\lambda$ can be found using the equation $E = \frac{hc}{\lambda}$, solving for $\lambda$ gives $\lambda = \frac{hc}{E}$. Substituting $h = 6.63 \times 10^{-34}\, \text{J⋅s}$, $c = 3.00 \times 10^8\, \text{m/s}$, and $E = 4.0 \times 10^{-19}\, \text{J}$ gives $\lambda \approx 497\, \text{nm}$.

A Light Beam Is Shining on a Metal Target That