methods, chem, physics revision

diff --git a/physics/light-matter.md b/physics/light-matter.md
index c14d9983a7f85963172890c875ab929c47f6aa3c..6630fd3f1bfe20f57f5d7c6eb9dbbd5c635632ed 100644 (file)
--- a/physics/light-matter.md
+++ b/physics/light-matter.md
@@ -105,7 +105,8 @@ $$\rho = {hf \over c} = {h \over \lambda}$$
 
 
 ### Absorption
-- Black lines in spectrum show light not reflected  
+- Black lines in spectrum show light not reflected
+- Frequency of a photon emitted or absorbed can be calculated from energy difference: $E_2 – E_1 = hf$ or $= hc$
 
 ### Emission
 
@@ -149,7 +150,7 @@ $$\sigma E \sigma t \ge {h \over 4 \pi}$$
 
 where $\sigma n$ is the uncertainty of $n$
 
-**$\sigma E$ and $\sigma t$ are inversely proportional$**
+**$\sigma E$ and $\sigma t$ are inversely proportional**
 
 Therefore, position and velocity cannot simultaneously be known with 100% certainty.
 
@@ -166,6 +167,17 @@ Therefore, position and velocity cannot simultaneously be known with 100% certai
 
 **Quantum mechanical model** - electron clouds rather than discrete shells (electrons are not particlces). We can only calculate probability of an electron being observed at a particular position
 
+Newton's and Einsteins models work together  
+
+### Photon-electron interaction
+
+When a photon collides with an electron, momentum is transferred to electron.
+
+$$\rho_{\text{photon}}={h \over \lambda}$$
+$$E=\rho c$$
+
+
+
 
 
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