[spec] render vectors cheatsheet

diff --git a/physics/fields2.md b/physics/fields2.md
index 4b5439aebdd097ec5572081f88a37d8ad4895f2c..8732c53387394929d60d6bf8ccde600017340fd3 100644 (file)
--- a/physics/fields2.md
+++ b/physics/fields2.md
@@ -8,6 +8,9 @@ Non-contact forces:
 - - magnetic fields (dipoles only)
 - gravitational force (monopoles only)
 
+Gravitational & -ve electric monopoles - field lines radiate towards central object
+Magnetic & electric dipoles - field lines go from + to -, or N to S
+
 ---
 
 ## Gravity
@@ -65,6 +68,7 @@ Area under field-distance graph = $\Delta E_g / \operatorname{kg}$
 - field lines always go from N -> S
 - dot means out of page, cross means into page
 - ${E_1 \over E_2}={r_1 \over r_2}^2$
+- flux: change in magnetic field
 
 
 ## Electric fields
@@ -119,6 +123,7 @@ $$E=k{Q \over r^2}$$
 ### Lenz's law
 - Right hand grip rule (relationship between directions of $I, F$)
 - Eddy currents counter movement within a field
+- Represented by -ve sign in Faraday's law
 
 ### Solenoids
 - Coil around core (like a transformer but field is transferred to kinetic energy)