Alternative text (alt text) is meant for readers who cannot see an image, such as blind readers and readers who use a text or mobile browser. It should summarize an image's purpose, and should not duplicate its caption. Every image should have alt text, except for purely decorative images, which should instead have "|alt=|link=".
Drude model
The following table shows images and captions on the left, and alt text and captions on the right: the right column is what a visually impaired reader will hear. This table was computed from the copy of Drude model cached on 02 May 2013 at 09:02.
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Drude Model electrons (shown here in blue) constantly bounce between heavier, stationary crystal ions (shown in red).
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 and that  . |
Complex conductivity for different frequencies assuming that
and that . |
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