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diff --git a/Light.md b/Light.md
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+++ b/Light.md
@@ -7,4 +7,11 @@ $$E=hf$$
 
 1. The maximum KE of ejected electrons is independent of intensity, but dependent on frequency $n$
 2. There is a minimum frequency n0below which there is no emission
-3. No time delay (less than 1 ns) before the onset of emission –but the rate of electrons depends on the intensity.
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+3. No time delay (less than 1 ns) before the onset of emission –but the rate of electrons depends on the intensity.
+
+![[photo-electric.png]]
+![[fermi-vacuum-level.png]]
+
+![[em-spectrum.png]]
+-   Radio spectrum
+	-   30Hz – 300 GHz
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@@ -0,0 +1,26 @@
+## Rank
+-   Number of indices
+-   Basis vectors per dimension/component
+-   0
+	-   Scalar
+-   1
+	-   Column Vector
+-   2
+	-   Square Matrix
+-   3
+	-   Cube matrix
+
+Matrices are not inherently rank-2 tensors. Matrices are just the formatting structure. The tensor described by the matrix must follow the transformation rules to be a tensor
+![[tensor.png]]
+# Transformation Rules
+
+1. Transforms like a tensor
+2. Invariant to a change in coordinate system
+	- Components change according to mathematical formulae
+
+## Dimension
+-   Dimensionality to the rank = number of components
+
+An $n$-[rank](https://mathworld.wolfram.com/TensorRank.html) tensor in $m$-dimensional space is a mathematical object that has $n$ indices and $m^n$ components and obeys certain transformation rules
+
+From <[wolfram](https://mathworld.wolfram.com/Tensor.html)>
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