Question

Calculate the wavelength of the light required to eject a photoelectron from caesium metal with a kinetic energy of 2.0 x 10 ^-19 J (v° for caesium is 4.55 x 10^14 Hz.

Answer 1

Answer on Question # 69998, Chemistry / Inorganic Chemistry

Calculate the wavelength of the light required to eject a photoelectron from caesium metal with a kinetic energy of $2.0 \times 10^{-19} \, \text{J}$ (v for caesium is $4.55 \times 10^{14} \, \text{Hz}$)?

Solution:

1. Calculate the general energy:

$$K_{\max} = h \times f - \Phi_0$$ $$K_{\max} = 6,63 \times 10^{-34} \times 4.55 \times 10^{14} - 2.0 \times 10^{-19} = 1.0 \times 10^{-19} \, (J)$$

2. Calculate the wavelength:

$$K_{\max} = \frac{h \times c}{\lambda} \Rightarrow \lambda = \frac{h \times c}{K_{\max}}$$ $$\lambda = \frac{6,63 \times 10^{-34} \times 3 \times 10^8}{1.0 \times 10^{-19}} = 198.9 \times 10^{-8} \, (m)$$

Answer: $198.9 \times 10^{-8} \, (m)$

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