The question asks for the wavelength associated with a frequency of $50 \, \text{kHz}$. Although the question mentions an "electron produced from the surface of a metal," the given frequency is characteristic of an electromagnetic wave. We will calculate the wavelength of an electromagnetic wave with this frequency. Step 1: Convert the given frequency from kilohertz (kHz) to hertz (Hz). The frequency $f = 50 \, \text{kHz}$. Since $1 \, \text{kHz} = 10^3 \, \text{Hz}$, $$ f = 50 \times 10^3 \, \text{Hz} $$ Step 2: Use the formula relating the speed of light ($c$), wavelength ($\lambda$), and frequency ($f$). The speed of light in a vacuum is approximately $c = 3.00 \times 10^8 \, \text{m/s}$. The formula is: $$ c = \lambda f $$ To find the wavelength, rearrange the formula: $$ \lambda = \frac{c}{f} $$ Step 3: Substitute the values and calculate the wavelength. $$ \lambda = \frac{3.00 \times 10^8 \, \text{m/s}}{50 \times 10^3 \, \text{Hz}} $$ $$ \lambda = \frac{3.00 \times 10^8}{5.0 \times 10^4} \, \text{m} $$ $$ \lambda = \left(\frac{3.00}{5.0}\right) \times 10^{8-4} \, \text{m} $$ $$ \lambda = 0.6 \times 10^4 \, \text{m} $$ $$ \lambda = 6 \times 10^3 \, \text{m} $$ Step 4: Compare the calculated wavelength with the given options. (A) $6 \times 10^{-6} \, \text{m}$ (B) $6 \times 10^3 \, \text{m}$ (C) $5 \times 10^{-6} \, \text{m}$ (D) $5 \times 10^3 \, \text{m}$ The calculated wavelength matches option (B). The final answer is $\boxed{\text{B) } 6 \times 10^3 \, \text{m}}$. That's 2 down. 3 left today — send the next one.