What is light energy?

Question

Can you give me a good explanation for it?

Answer 1

Energy, by definition is the capability to do work or cause a change. Light energy is its capability to do work or cause a change.

Light energy does work, for example, when it strikes a photoelectric cell and bounces off electrons. It causes a change, for example, when it strikes film and causes it to change shades and color.

Light energy is proportional to the frequency of that light. Higher frequencies carry higher capabilities and, therefore, higher energies. The equation for light energy is E = hf; where h is a constant of proportionality called Planks constant and f is the frequency of the light.

It can be shown that, for light, its wavelength L = ct; where c = speed of light in some medium (e.g., a vacuum), t = time light travels one wavelength (which is called its period). But t = 1/f so that the period of light is just the reciprocal of its frequency.

Then from E = hf = h/t = hc/L, which shows that energy is inversely proportional to the wavelength of that light. In other words, blue, for example, has a shorter wavelength than red; so blue carries more energy than red.

Answer 2

What Is Light Energy