Finding Image Position of Point Object by Two Radii

[Jacob87411]

A piece of glass has two radii. The left side has a radius of 2 cm and the right has a radii of 4 cm. The two are separated by 8 cm. There is a point object 1 cm left of the glass, find the position of the image.


I need to use the equation

n2-n1/R = n1/do + n2/di, i need to use it twice, once for each radius, and one time it would be negative (the radius).

1.5-1 / .02 = 1/.01 + 1.5/di

Solved it and got di=2 cm

1.5-1/-.04 = 1/.09 + 1.5/di

Solved it got di to be -12 cm.

Combined the two to get -12 + 2 = -10 cm..10 cm behind the piece of glass...does this seem right?

 

[jtbell]

For the second surface, the "object" is not the original object, but instead, the image formed by the first surface. So the object distance in the second step is the distance from the second surface to the image that you calculated in the first step. The second image distance is the final image distance (from the second surface).

 

[thepatientmental]

Yes, your calculations and solution seem correct. The image of the point object would be located 10 cm behind the piece of glass. It is important to note that the negative sign in front of the 12 cm indicates that the image is located on the opposite side of the glass, which makes sense since the object is located on the left side of the glass. Good job using the equation and solving for both radii separately.