Warm-Up Exercise 35

Due 12:15 pm, Fri 16 Nov 2012

Physics 123, Fall 2012

Reading assignment: 38.3-38.5

Cat's eyes have pupils that can be modeled as vertical slits. At night would cats be more successful resolving the headlights of a far away car if the car is horizontal (regular) or tilted vertically? Explain.

Vertical slits will cause a point of light to be spread out more in the horizontal direction than in the vertical. Therefore vertically oriented lights will overlap each others' "spreading out" less than horizontally oriented lights, and will be easier to resolve.

Suppose you are trying to resolve a binary star system with a telescope. Can you improve the resolving power (increase the resolution) using a color filter? Explain.

Yes. The diffraction caused by a telescope aperture (which does become a limiting factor) depends on wavelength as per eqn 38.6 (8th edition). Using a smaller wavelength via e.g. a blue filter will aid the resolving power.

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