Question

UV-A is a type of radiation that reaches the Earth's surface from the sun. UV-A has a wavelength of 320 nm and UV-B has a wavelength of 280 m. Most sunscreens protect against these two types of UV radiation. a) Which UV radiation has the highest energy? Justify with calculations.

Answer 1

Answer: UV-A radiation has a wavelength of 320 nm, while UV-B radiation has a wavelength of 280 nm . The energy of a photon is inversely proportional to its wavelength, so the shorter the wavelength, the higher the energy of the photon .

To calculate the energy of a photon, we can use the formula:

E = hc/λ

where E is the energy of the photon, h is Planck’s constant (6.626 x 10^-34 J s), c is the speed of light (2.998 x 10^8 m/s), and λ is the wavelength of the photon in meters .

Using this formula, we can calculate the energy of a UV-A photon as follows:

E = hc/λ = (6.626 x 10^-34 J s) x (2.998 x 10^8 m/s) / (320 x 10^-9 m) = 1.96 x 10^-19 J

Similarly, we can calculate the energy of a UV-B photon as follows:

E = hc/λ = (6.626 x 10^-34 J s) x (2.998 x 10^8 m/s) / (280 x 10^-9 m) = 2.24 x 10^-19 J

Therefore, UV-B radiation has a higher energy than UV-A radiation .