How does a magnifying glass light up a matchstick

The magnifying glass uses a convex lens.Therefore,when beams of light passes through the lens,it will be focus onto a focal point.As the tip of the matchstick is made up of flammable chemical,a single point of light will cause the temperature to be high enough to have a chemical reaction with the matchstick,thus lighting it up.

Source:mcat-review.org/light-geometrical-optics.php
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