uv rays

[luckyman]

we see people at beach using silver foil to lie on to attract sun rays.....does a mirror or silver foil attract the sun more....do uv rays bounce back of the foil material and come back to tan/burn the skin?

[gen2]

Firstly, NOTHING attracts light, either visible or otherwise.

UV light behaves the same as visible light in respect of refraction and reflection and so, yes, it will reflect off foil and add to the tanning. Skiers and mountaineers are familiar with this where UV reflected off the snow and ice can cause sunburn when the intensity of the direct sunlight alone would not be strong enough. They wear 'Glacier Cream' to protect themselves.

UV light is of course damaging to skin cells and has been implicated in causing some forms of skin cancer.

[gen2]

An amendment to the above:

An extremely strong gravitational field can attract light and that is why black holes are black. The gravity is so strong, light that enters it is held permanently and cannot escape. Less strong gravitational fields have a lensing effect, bending light that passes nearby.