I’ve been working on moving a couple of Geophysics courses over to WordPress blogs recently, and the latest one includes a lot of mathematical equations.

The previous version of the course was displaying these as images without any titles or alt tags, so I thought I would improve on their accessibility by using HTML entities, several of which were new to me, and it has been an interesting journey!

### Here are some of the new scientific HTML entities I discovered today:

Symbol HTML Entity Code Entity number Name
ρ `&rho;` &#961; Rho (represents densities: mass density, air density or charge density)
`&sim;` &#8764; Similar to
π `&pi;` &#960; Pi (3.14 etc)
° `&deg;` &#176; Degree (ok I have used this one before!)
Ω `&Omega;` &#937; Omega (symbol for ohms, the units of electrical resistance)
² `&sup2;` &#178; Squared (I would have used superscript, but specific codes exist for squared and cubed)
³ `&sup3;` &#179; Cubed
Δ `&Delta;` &#2206; Increment / Delta
`&sime; doesn't work` &#8771; Asymptotically equal to
# `(none)` &#035; Number sign
τ `&tau;` &#932; Tau, the symbol for tortuosity in hydrogeology
Φ `&Phi;` &#934; Phi, symbol for porosity
`&radic;` &#8730; Square root
`&frasl;` &#8260; Fraction slash
`&sdot;` &#8901; Dot operator
θ `&theta;` &#952; theta
`&rarr;` &#8594; Right arrow
δ `&delta;` &#948; delta
ω `&omega;` &#969; omega
`&asymp;` &#8776; Almost equal to
μ `&mu;` &#956; mu
ε `&epsilon;` &#949; epsilon
σ `&sigma;` &#963; sigma
`&Gt; (doesn't work)` &#8811; Much Greater-Than
`&ge;` &#8805; Greater-Than or Equal To

So now I can say `k=(ρ2 - ρ1)/(ρ2 + ρ1)` instead of

And here’s a page with a LOT of these: Resistance and Resistivity

Fun times! 😎 (that’s `&#x1F60E;` to you 😁)