need help

• Take  an equation from this course, and describe the equation using simple  language to demonstrate your understanding (analogies are helpful).  Write the name of equation (or descriptor) in the title of your post  (e.g., "Coulomb's Law" or "Input impedance of a loaded transmission  line"). Once an equation has been posted, you must choose another equation to examine (no repeats).
• Describe a real world engineering situation, in which this equation would be use for modeling, analysis, and design. 
• What emerging and/or future technologies could depend on this equation?
• Your post should be at least four paragraphs (with four sentences per paragraph). 

pick another than those topics 1- reflection coefficient 2- Electric Potential3- Gauss's Law4- Faraday's second law of electromagnetic Induction5- Phase Velocity  6-      The Biot-Savart Law 7-  Thread: Electromagnetic Spectrum Wave (Wavelength)