A teacher uses an overhead projector for showing slides in a classroom, but students complained that the image is too small. The teacher then enlarged the image by moving the projector away from the screen, but the image becomes blurred. The image would get clear again by
A. Moving the lens closer to the slide.
B. Moving the lens farther from the slide.
C. Decreasing the amount of light in the room.
D. Increasing the power of the projector lamp.
with explanation please, thank!
optics (1 question only)
2007-01-17 3:44 am
回答 (2)
2007-01-17 4:10 am
✔ 最佳答案
Ans: AImage distance has increased, object distance should decrease in order to get a clear image.
Lens formula: 1/u + 1/s = 1/f
u: object distance
s: Image distance
f : focal length
2007-01-17 4:12 am
The answer is A.
2007-01-16 20:22:02 補充：
Real object & real image, so it is effectively a "convex" lens (with object dist. & image distance focal length). By drawing a ray diagram or by applying "1/u 1/v = 1/f", it can be shown that: in order for the image distance to go UP, the object distance has to go DOWN.
2007-01-16 20:22:02 補充：
Real object & real image, so it is effectively a "convex" lens (with object dist. & image distance focal length). By drawing a ray diagram or by applying "1/u 1/v = 1/f", it can be shown that: in order for the image distance to go UP, the object distance has to go DOWN.
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