37.   A hunter who is a bit of a braggart claims that from a distance of 1.6 km he can selectively shoot either of two squirrels who are sitting ten centimeters apart on the same branch of a tree. What’s more, he claims that he can do this without the aid of a telescopic sight on his rifle. (a) Determine the diameter of the pupils of his eyes that would be required for him to be able to resolve the squirrels as separate objects. In this calculation use a wavelength of 498 nm (in vacuum) for the light. (b) State whether his claim is reasonable, and provide a reason for your answer. In evaluating his claim, consider that the human eye automatically adjusts the diameter of its pupil over a typical range of 2 to 8 mm, the larger values coming into play as the lighting becomes darker. Note also that under dark conditions, the eye is most sensitive to a wavelength of 498 nm.

 

Solve for the diameter

 

Since the diameter 9.7 mm > 8 mm which would suggest that it is unlikely that the hunter can do this unless he has an eye which expands the size of his pupil beyond what is normal.

 

The claim is unreasonable as he would need to be able to create a larger diameter pupil than most people can.

 

 

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This page last updated on July 13, 2018