Should change the "alt" tag of img to "title" tag. It may be helpful for readers to see the tex souce code of all equations.
Such as: change the following line of page < http://en.wikipedia.org/wiki/Planck_constant >
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<img class="mwe-math-fallback-image-inline tex" alt="E = h\nu \,." src="//upload.wikimedia.org/math/6/0/1/601847ec59090015aeade4029d7683ff.png">
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to
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<img class="mwe-math-fallback-image-inline tex" title="E = h\nu \,." src="//upload.wikimedia.org/math/6/0/1/601847ec59090015aeade4029d7683ff.png">
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Then, when we put mouse pointer on the equation img, it will show the code of the equation.
The old "alt" tag will only do this for old ie, but "title" tag does well for all browsers.