Light Equations, | NemoQuiz

Physical Constants:

c = 299 792 458 m/s (exact speed of light)
c = 3.00 x 10⁸ m/s (approximate speed of light)

h = 6.626 x 10⁻³⁴ J⋅s (Planck’s constant)

Relevant equations related to light and modern physics:

$c = \lambda f$

This first equation is based on the regular wave equation, v = λf.
Instead of “v” for speed, we have “c” for the speed of light. You can calculate the wavelength of light if you know its frequency, and vice versa.

$E = hf = \cfrac{hc}{\lambda}$

This equation gives the energy of a single photon of light given its frequency. Or, you can use the second half of the equation to calculate a photon’s energy from its wavelength. The equations include Planck’s constant, h.

$p = \cfrac{h}{\lambda} = \cfrac{hf}{c}$

This equation has two interesting uses.
1) If you know the wavelength or frequency of a light photon, you can calculate its momentum, p.
2) You can calculate the De Broglie wavelength of any particle, such as an electron, if you know its momentum, p.

$E = mc^2$

This equation shows a relation between mass and energy. The speed of light, c, appears in the equation.