物理--光的折射【透鏡】

用戶82677

2009-01-01 11:49 pm

請問……

箭長10cm，置於焦距為15cm之凸透鏡一側，箭桿與主軸相合，箭頭指向光心，並距離透鏡30cm。求箭像的位置、長度及其所指向的方向。

回答 (1)

天同

2009-01-02 12:53 am

✔ 最佳答案

Consider the arrow head,
object distance u = 30 cm, focal length of lens = 15 cm
hence, 1/30 + 1/v = 1/15
where v is the image distance of the arrow head
solve for v gives v = 30 cm
Consider the arrow tail,
u = (10+30) cm = 40 cm
hence, 1/40 + 1/v' = 1/15
where v' is the image distance of the arrow tail
solve for v' gives v' = 24 cm
Thus, the image of the arrow head is situated on the other side of the lens at a distance of 30 cm from it, with an image length of (30-24) cm = 6 cm.
The image is real, with the arrow pointing away fromthe lens.

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