wave motion (urgent)

2011-12-08 2:21 am

圖片參考：http://farm8.staticflickr.com/7159/6470832161_bfe35a4815_b.jpg

5. ans: D how can (2) increase the internal energy of an object?
6. ans: D, why is the ans D but not B?
15 ans: A, why is the ans A but not D?

thanks
thanks

更新1:

the ans I gave is the model ans to the questions. so for 6, u think the ans is B? what about 15? the model ans is A but I think it's D, so I want to know what's the correct ans

回答 (1)

天同

2011-12-08 3:02 am

✔ 最佳答案

5. There is work done and hence produce heat, which raises the temperature of the block.

6. Try to draw the "rays", which are perpendicular to the wavefront, such as the given arrow. These rays will be undergone two reflections by the L-shape barrier, and will jsut reverse their directions. Thus the refected wavefront is as that shown in oprion B.

15. Are you aure that the answer is option A ?

2011-12-07 23:07:04 補充：
6. Option D is the wavefron after one reflection. Option B is the final wavefront after two reflections.

2011-12-07 23:11:39 補充：
15. Ray diagram sows that the image should be inverted.

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