What determines the rate at which energy is delivered by a current?

What determines the terrestrial ecosystem ?

An engine pumps water continuously through a hose Water leaves the hose with a velocity .v. and .m. mass per unit length of the water jet. What is the rate at which kinetic energy is imparted to water.

What determine the terrestiral ecosystems?

The charged currents in the outer conducting regions of the earth's core are thought to be responsible for earth's magnetism. What might be the 'battery' (i.e., the source of energy) to sustain these currents ?

A 100 W sodium lamp radiates radiates energy uniformly in all directions. The lamp is located at the centre of a large sphere that absorbs all the sodium light which is incident on it. The wavelength of the sodium light is 589 nm. At what rate are the photons delivered to the sphere ?

What are the factors which influence electromagnetic energy '?