PX154 - I1 - the nature of light

light is an EM wave, it can propagate through vacuum
maxwell developed equations to describe electronic and magnetic fields. he realized these equations could be solved in the absence if any charges or magnets
in a vacuum, two equations can be obtained:

\frac{\partial^{2} E}{\partial x^{2}} = ϵ_{0} μ_{0} \frac{\partial^{2} E}{\partial t^{2}} $ $ $ $ \frac{\partial^{2} B}{\partial x^{2}} = ϵ_{0} μ_{0} \frac{\partial^{2} B}{\partial t^{2}}

where, $ϵ_{0} =$ permittivity of free space, and $μ_{0} =$ permeability of free space
- wave equations!
- we have, the wave speed:
$$v = \frac{1}{\sqrt{\epsilon_{0}\mu_{0}}} = c$$
- comments:
- the wave is a combination oscillating electric and magnetic fields
- both travel together
- they are transverse

E and B fields are perpendicular to each other and to the direction of propagation
the E-field is largely responsible for the interactions between light and matter
B- field only has a small magnitude
the E and B fields are vector quantities
for a wave propagation along $x$ , we might have:
\1\n\2\n