From 3de4db753452e50a0736e77ff8fbd26dca73c428 Mon Sep 17 00:00:00 2001
From: eggy <danielchen04@hotmail.ca>
Date: Thu, 12 Jan 2023 11:31:40 -0500
Subject: [PATCH] ece140: add power

---
 docs/1b/ece140.md | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/docs/1b/ece140.md b/docs/1b/ece140.md
index 56ac0f3..25a6979 100644
--- a/docs/1b/ece140.md
+++ b/docs/1b/ece140.md
@@ -23,3 +23,18 @@ $$i=\frac{dw}{dq}=\frac{i}{R}$$
 
 $$i=\frac{dq}{dt}\approx \frac{\Delta q}{\Delta t}$$
 
+### Power
+
+Power represents the rate of doing work, in unit watts ($\pu W$, J/s)
+
+$$P=\frac{dw}{dt}$$
+
+It is also directly related to voltage and current:
+
+$$P=vi$$
+
+Much like relative velocity, power is directional and relative, with a positive sign indicating the direction of conventional current.
+
+$$P_{CB}=-P_{BC}$$
+
+The **ground** is the "absolute zero" voltage with a maximum potential difference. It is also known as the "reference voltage".