Biconvex lens with one known surface radius

[Jacob87411]

An object is located 36 cm to the left of a biconvex lens of index of refraction 1.5 The left surface of the lens has a radius of curvature of 20 cm. The right surface of the lens is to be shaped so that a real image will be formed 72 cm to the right of the lens. What is the required radius of curvature of the second surface?

Need some clarification on how to approach this. We have that 1.5 = C/v and thus can figure out the speed the light will travel at off the lens. Is the image going to reflect off the left side then the right, like its two lens? If so I will need to use 1/f=1/d0 + 1/di. Any help is appreciated

 

[member 553083]

. The radius of curvature of the second surface is 40 cm. To solve this problem, you can use the lens equation 1/f = 1/d0 + 1/di, where f is the focal length, d0 is the object distance, and di is the image distance. Since we know that the object distance is 36 cm and the image distance is 72 cm, we can solve for the focal length, which is 48 cm. Since 1.5 = C/v, we can calculate the speed of light through the lens. Then, we can use the equation f = (1/2)*(n-1)*C to calculate the required radius of curvature of the second surface, which is 40 cm.

 

[thepatientmental]

.

To calculate the required radius of curvature for the second surface of the biconvex lens, we can use the thin lens equation 1/f=1/d0 + 1/di, where f is the focal length, d0 is the object distance, and di is the image distance.

In this problem, the object distance (d0) is given as 36 cm and the image distance (di) is given as 72 cm. We can also determine the focal length (f) by using the given information about the index of refraction and the radius of curvature of the first surface.

Using the formula f = R/2n, where R is the radius of curvature and n is the index of refraction, we can calculate the focal length of the lens as f = 20 cm/2(1.5) = 6.67 cm.

Substituting these values into the thin lens equation, we get 1/6.67 = 1/36 + 1/72. Solving for di, we get di = 24 cm.

Since the image is formed 72 cm to the right of the lens, the image distance (di) is positive. This means that the image is formed on the same side as the object, which indicates that the light rays are not reflected off the second surface of the lens.

Therefore, we can conclude that the required radius of curvature for the second surface of the biconvex lens is infinity (flat surface). This means that the second surface of the lens needs to be a flat surface in order to form a real image at a distance of 72 cm to the right of the lens.