Reading Glasses Blue
Physics Help!?
1.) If you fire a bullet through a tree, it will slow down in the tree and emerge at less than its initial speed. But when light shines on a pane of glass, even though it slows down inside, its speed upon emerging is the same as its initial speed. Why?
2.) Which takes longer to get through glass-red or blue light?
(My answer: I am guessing it is blue light, but not sure.)
3.) Sunlight is hitting Reading Glasses and sunglasses. Which pair of glasses will be warmer? Why?
(My answer: I believe it is reading glasses, but don't the exact reason why.)
4.) Why does a high-flying plane cast little or no shadow on the ground, while a low-flying plane casts a sharp shadow?
5.) What percentage of light would be transmitted by two ideal polarizing filters, one atop the other, with their axes aligned? With their axes crossed at right angles?
Help is truly appreciated.
1) Some of the bullet's energy is converted to heat, leaving it with less KE than when it entered. The beam of light loses virtually no energy, and what energy is lost results in an exiting beam with less intensity, but the same speed, dependent only on the index of refraction of the medium.
2) Blue light is slowed more than red while transiting glass.
3) The sunglasses will absorb more of the energy in the light and convert it to heat.
4) The penumbra effect. At close proximity to the ground, only a small percent of the sun's rays can get around the outline of the plane to diffuse the edges of the shadow. At high altitude, nearly all the rays do so. If the sun were a point source of light, the shadow would be sharp at any height.
5) a) Each will absorb ½ the light incident on it, so ½*½ = ¼
....b) Lo = Li*cos²Θ; when Θ = 90°, Lo = 0