How Does a Spherometer Measure Curvature?

[blackcat]

I'm trying to figure out what/how to use one without seeing/having one.

Am I right in saying the following.

It has three legs, which form the vertices of an equilateral triangle. The centre leg is placed onto a lens, and it's adjusted until they all balance/evne out. Then the distance of it has been adjusted is noted, and put into this formula (on wikipedia I found);

r = [ (a^2 + 3h^2)/6h ]

in which a = distance between feet, and h is the distance it's been adjusted.

Is there a diagrammatical representation of this? Can someone correct any mistakes?

Thanks

 

[OlderDan]

I'm trying to figure out what/how to use one without seeing/having one.

Am I right in saying the following.

It has three legs, which form the vertices of an equilateral triangle. The centre leg is placed onto a lens, and it's adjusted until they all balance/evne out. Then the distance of it has been adjusted is noted, and put into this formula (on wikipedia I found);

r = [ (a^2 + 3h^2)/6h ]

in which a = distance between feet, and h is the distance it's been adjusted.

Is there a diagrammatical representation of this? Can someone correct any mistakes?

Thanks

There are three fixed legs separated by distance a and an adjustable leg in the center of the triangle.

http://physics.kenyon.edu/EarlyApparatus/Optics/Spherometer/Spherometer.html

The flat disk is engraved with the markings to show the d value. The vertical flat is aligned with the markings to read d.

 

[kyle8921]

Using a spherometer may seem daunting at first, but with a little guidance, it can be a valuable tool in measuring the curvature of lenses and other curved surfaces. The first step is to ensure that the spherometer is set up correctly. As you mentioned, it has three legs that form an equilateral triangle. The center leg should be placed on the surface you want to measure, while the other two legs should be resting on a flat surface. This will ensure stability and accuracy in your measurements.

Next, you will need to adjust the center leg until it is level with the other two legs. This can be done by turning the knob on top of the center leg, which will raise or lower it. Once all three legs are level, you can take your measurement. The distance the center leg was adjusted is important, as it will be used in the formula you mentioned (r = [(a^2 + 3h^2)/6h]). The "a" in this formula refers to the distance between the outer two legs, and the "h" refers to the distance the center leg was adjusted. This formula will give you the radius of curvature of the surface you are measuring.

To answer your question about a diagrammatical representation, there are several diagrams available online that show the setup and use of a spherometer. It may also be helpful to watch a video tutorial or have someone demonstrate the process for you in person.

I hope this explanation helps you understand how to use a spherometer. It may take some practice to get comfortable with, but with proper setup and use, it can be a valuable tool in your scientific endeavors.