It requires about 3.9 eV of energy to break apart or severely damage a DNA molecule. When we damage the DNA in our skin cells, our bodies respond by directing a lot of blood to repair and replace the damaged cells, and our skin takes on a bright red glow (the tell-tale signs of sunburn). We also increase our risk of skin cancer.

a. What wavelength of light, in nm, has just enough energy to damage our DNA?
b. Which wavelengths of light are most important for a good sunscreen to block?
i. Wavelengths very close to the one calculated in the previous question
ii. Wavelengths greater than or equal to the one calculated in the previous question.
iii. Wavelengths less than or equal to the one calculated in the previous question.
iv. All wavelengths are equally important to block.
c. Only about 1% of the total power of sunlight that we are exposed to is in the form of dangerous radiation. Why is it that this 1% can cause damage to our DNA, but exposure to the other 99% leaves our DNA unharmed? How does this relate to the observations from the photoelectric effect