Question

how to determine focal lenght on a concave lens by combination method​

Answer 1

Explanation:

Note the value of u and v. You can calculate the focal length (F) of combination of lenses using the formula F = uv/(u+v). The focal length of convex lens (f1) is shown inside the simulator window. You can calculate the focal length of the concave lens using the formula f2 = (f1F/(f1-F).