## Chemistry: The Central Science (13th Edition)

- The frequency of the radiation is: $\nu \approx4.612\times10^{14}s^{-1}$ - The color red is associated with a wavelength of $650nm$.
*Strategy: We would use the formula $$\lambda\times\nu=c$$ in which $\lambda$ : wavelength of radiation $\nu$ : frequency of radiation $c$ : speed of light (we would take the speed of light in a vacuum, meaning $c \approx2.998\times10^8m/s$) - Step 1: Find the known variables The laser pointer emits light at 650nm, so the wavelength of this radiation is: $\lambda = 650nm = 6.5\times10^{-7}m$. - Step 2: Do the calculation according to the formula The frequency of this radiation would be: $\nu=\frac{c}{\lambda}=\frac{2.998\times10^{8}}{6.5\times10^{-7}}\approx4.612\times10^{14}s^{-1}$ - Step 3: Predict the color of this radiation Looking up the electromagnetic spectrum, we see that a wavelength of $650nm$ would very likely lie in the red zone of the visible light. Therefore, red is associated with this wavelength