How many electrons are in an sn+2 ion?

A150 w lamp emits light of wavelength 590 nm uniformly in all directions. what is the photon flux (photons per unit area per unit time) on a small screen at a distance 2.3 m from the lamp? assume the photons are uniformly distributed over the surface of a sphere of radius 2.3 m.

How can you increase the strength of an electromagnet?

An electron is traveling with initial kinetic energy k in a uniform electric field. the electron comes to rest momentarily after traveling a distance d. (a) what is the magnitude of the electric field