on . Posted in Classical Mechanics

Radiant energy, abbreviated as $$E_r$$, is energy that travels in the form of electromagnetic waves, such as light, radio waves, microwaves, and X-rays.  It's a type of energy that doesn't require a medium (like air or water) to propagate, it can travel through a vacuum as well as through various materials.  Radiant energy is a fundamental concept in physics and is closely related to the behavior of electromagnetic radiation.  Electromagnetic waves consist of oscillating electric and magnetic fields that move through space.  These waves carry energy with them and can interact with matter in various ways.  Radiant energy can be found across the electromagnetic spectrum, which includes different types of electromagnetic waves with varying wavelengths and frequencies.

• Visible Light  -  This is the range of electromagnetic radiation that can be detected by the human eye.  It includes colors ranging from violet to red.
• Infrared Radiation  -  This type of radiation has longer wavelengths than visible light and is often associated with heat.  It's used in technologies like thermal imaging.
• Ultraviolet Radiation  -  UV radiation has shorter wavelengths than visible light and is known for its effects on biological organisms, such as causing sunburn.
• Radio Waves  -  These have much longer wavelengths than visible light and are commonly used for communication, such as radio and television broadcasting.
• X-rays and Gamma Rays  -  These types of radiation have very short wavelengths and high energies.  They're often used in medical imaging and can penetrate through materials.

Radiant energy can be absorbed, reflected, transmitted, or emitted by various materials and substances, depending on their properties.  For example, when light strikes an object, it can be absorbed, causing the object to heat up, or it can be reflected, allowing us to see the object.

$$\large{ E_r = \sigma \; T_a^{4} }$$      (Radiant Energy)

$$\large{ \sigma = \frac{ E_r }{ T_a^{4} } }$$

$$\large{ T_a = \left( \frac{ E_r }{ \sigma } \right)^{ \frac{1}{4} } }$$

Symbol English Metric
$$\large{ E_r }$$ = radiant force $$\large{lbf-ft}$$ $$\large{J}$$
$$\large{ \sigma }$$  (Greek symbol sigma) = Stefan-Boltzmann constant $$\large{\frac{Btu}{ft^2\;hr\; R^4}}$$  $$\large{ \frac{W}{m^2-K^4} }$$
$$\large{ T_a }$$ = absolute temperature $$\large{R}$$ $$\large{K}$$