Parabolic Reflector Part 1 Drawing and Measuring the Parabola

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[@johnburens3395]

Clearly Isaac Newton had a full command of graphing skills to be able to calculate and design his reflector. I'm glad I took algebra. Thanks for the post!

[@shanegibbens]

Thanks Man, it just seems so difficult for people to just explain the math for this lol. Everyone is quick to show how mirrors works, but no one wants to explain how to figure it out.

[@buzzwerd8093]

You can construct a parabola on lined paper using a compass and the focus-directrix technique. Every point on the parabola is as far above the directrix (a horizontal line below the focus point) as it is distant from the focus. The bottom of the parabola is halfway between the focus and the directrix. For a 6" focus, put the bottom point on one line and the focus 6 lines above then open the compass to 7" and cross the next line up from the bottom on left and right with the compass. Then the next line at 8", next at 9", etc. No algebra necessary, this is how the ancient Greeks constructed parabolas. You can draw an ellipse with 2 pins, string and a pencil. A half ellipse the long way will focus on a point.

[@eyrron]

Much appreciated!

[@rantallion5032]

perfect - thanks

[@bisdaktv8856]

Hi sir. Good day thanks for sharing your knowledge.. by the way, what materials are best to use as reflector? Thanks and hope you can answer😊

[@leolexfacundo9918]

copper

[@user-il5ls3vf1f]

My respected sir and the planner for how to read the sun on the saucer, please, sir, the translation of Arabic, and you have great doubts and make you an asset for the nation. With regards to you

[@SideWalkAstronomyNetherlands]

PleaSE.... "inches" ...nobody uses those... get real, use cm/mm, come on..., you can do it, it's not hard..