F.3 PHY~Lens

wisdoman

An object is placed in front of a converging lens. An image is formed 30 cm in front of the lens. The focal length of the lens is 20cm.
A. Draw the ray diagram.
B. State the nature of the image.
C. Find the magnification.
D. Find the object distance.
我想問點搵個object/image幾高? 定係自己let佢幾多就幾多?
同埋點知佢係real/virtual image?
thx[[bao_26]]

[ 本帖最後由 wisdoman 於 25-5-2008 22:32 編輯 ]

Zend

2. nature of image
magnified, upright, vitural
其他請你自己做~

[S]【YU】

C/D similar triangle, simple ratio.

wisdoman

An object located in front of a diverging lens. An image is formed 30 cm from the lens. The focal length of the lens is 50cm
Draw the ray diagram

咩係from the lens 呀...?個 lens右邊?
之後要點ar...help plz[[bao_29]]

[S]【YU】

diverging lens 得1種ray diagram.
object & image 一定係同一邊

sosai

我想問樓主問果題係唔係一定要用格仔紙畫先做到
同埋係唔係一定VITURAL

wisdoman

I have no idea for this question...  [[bao_29]]
An object is placed in front of a concave lens. A virtual image is formed in front of the lens. The focal length of the lens 20 cm and the magnification is 0.5.

A. Draw the ray diagram.

piyopiyo

原帖由 wisdoman 於 30-5-2008 19:17 發表
I have no idea for this question...  []
An object is placed in front of a concave lens. A virtual image is formed in front of the lens. The focal length of the lens 20 cm and the magnification is 0. ...

concave lens的image,如果我無推錯的話,一定係lens同focus中間[[m416]]
你畫左個image就拉得番個object出泥,因為object distance/image distance = 2
實會做到ge,你form幾[[m416]]

山本一

大大隻字係form 3-.-
但我中3 都味學佢過d-.-

Zend

原帖由 sosai 於 29-5-2008 11:22 PM 發表
我想問樓主問果題係唔係一定要用格仔紙畫先做到
同埋係唔係一定VITURAL

negative
以前CE有lens formula/lens equation

1/u+1/v=1/f
適用於convex/concave lens.
無記錯concex/concave mirror 都有類似的公式