A converging lens with the same curvature on both faces and a focal length of 25 cm is to be made from crown glass having a refractive index of 1.52. What radius of curvature is required for each face

Aphoton is absorbed by an electron that is in the n = 3 state of a hydrogen atom, causing the hydrogen atom to become ionized. very far away from the nucleus, the released electron has a velocity of 750,000 m/s. what was the wavelength of the absorbed photon?