A convex meniscus thin lens is made with the radius of curvature of the first convex surface being 25.0 cm and the second convex (towards object) surface 45.0 cm. If the glass used has index of refraction 1.500, what is the focal length of this lens?

Athin nonconducting rod with a uniform distribution of positive charge q is bent into a circle of radius r. the central perpendicular axis through the ring is a z-axis, with the origin at the center of the ring. a) what is the magnitude of the electric field due to the rod at z = 0? n/c (b) what is the magnitude of the electric field due to the rod at z = infinity? n/c (c) in terms of r, at what positive value of z is that magnitude maximum? r (d) if r = 4.00 cm and q = 9.00 µc, what is the maximum magnitude? n/c