When a beam of light strikes a surface, it transfers energy to that surface. The intensity of the beam is the energy transferred per unit area per unit time. What is the unit of intensity, written in SI base units?
- A$\text{kg m}^{-2}\,\text{s}^{-1}$
- B$\text{kg m}^2\,\text{s}^{-3}$
- C$\text{kg s}^{-2}$
- D$\text{kg s}^{-3}$