Edits to “Statement”, “Answer”
en/13.4.12.md
+2 −2
| @@ -1,11 +1,11 @@ | |||
| ### Statement | |||
| − | $13.4.12.$ | ||
| + | $13.4.12.$ How will the illumination of the image of the Sun given by a flat-convex lens change if the lens is cut in diameter and folded flat? | ||
| ### Solution | |||
| While folding a planoconvex lens along its diameter reduces its light-collecting area by a half, the new (half) biconvex lens has half the focal length and produces the image of the the Sun (which is very far) with half the diameter as well. Thus a half of the energy is concentrated on a quarter of the image area, and the intensity of the image of the Sun will double. | |||
| #### Answer | |||
| − | [Insert a concise answer or boxed result] | ||
| + | Double. | ||
| @@ -1,11 +1,11 @@ | |||
| ### Statement | ### Statement | ||
| $13.4.12.$ |
$13.4.12.$ How will the illumination of the image of the Sun given by a flat-convex lens change if the lens is cut in diameter and folded flat? | ||
| ### Solution | ### Solution | ||
| While folding a planoconvex lens along its diameter reduces its light-collecting area by a half, the new (half) biconvex lens has half the focal length and produces the image of the the Sun (which is very far) with half the diameter as well. Thus a half of the energy is concentrated on a quarter of the image area, and the intensity of the image of the Sun will double. | While folding a planoconvex lens along its diameter reduces its light-collecting area by a half, the new (half) biconvex lens has half the focal length and produces the image of the the Sun (which is very far) with half the diameter as well. Thus a half of the energy is concentrated on a quarter of the image area, and the intensity of the image of the Sun will double. | ||
| #### Answer | #### Answer | ||
| [Insert a concise answer or boxed result] | Double. | ||