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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 ρ ρ Rho (represents densities: mass density, air density or charge density)
∼ ∼ Similar to
π π π Pi (3.14 etc)
° ° ° Degree (ok I have used this one before!)
Ω Ω Ω Omega (symbol for ohms, the units of electrical resistance)
² ² ² Squared (I would have used superscript, but specific codes exist for squared and cubed)
³ ³ ³ Cubed
Δ Δ ࢞ Increment / Delta
≃ doesn't work ≃ Asymptotically equal to
# (none) # Number sign
τ τ Τ Tau, the symbol for tortuosity in hydrogeology
Φ Φ Φ Phi, symbol for porosity
√ √ Square root
⁄ ⁄ Fraction slash
⋅ ⋅ Dot operator
θ θ θ theta
→ → Right arrow
δ δ δ delta
ω ω ω omega
≈ ≈ Almost equal to
μ μ μ mu
ε ε ε epsilon
σ σ σ sigma
≫ (doesn't work) ≫ Much Greater-Than
≥ ≥ Greater-Than or Equal To

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

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

Fun times! 😎 (that’s 😎 to you 😁)


Update: Now this is a challenge…

Really complicated equation

Really complicated equation 😬

…to be continued

Main image: T-shirt with Maxwell’s Equations, by Eric Mesa on Flickr, license: CC BY-NC-SA 2.0

(Photo by Eric Mesa, via Flickr: