Convex and concave lenses form images by refraction, and the HESI A2 physics subtest expects you to name that image, real or virtual, upright or inverted, from the lens type and the object's position.
ObjectiveP.4.3Read4 minExam weightWaves, Sound and Light ≈ 20% of Physics
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Tell a convex (converging) lens apart from a concave (diverging) lens by shape and by the sign of its focal length.
Sort an image as real or virtual, and upright or inverted, from where the object sits relative to the focal point.
Apply the thin lens equation to find an image distance and its magnification.
What the lesson concludes
A convex lens is thicker through the middle and converges light to a positive focal length; a concave lens is thinner through the middle and diverges light to a negative focal length.
A real image forms where refracted rays actually cross, can be projected onto a screen, and is always inverted.
A virtual image forms where rays only appear to cross, cannot be projected onto a screen, and is always upright.
A concave lens used alone can only ever produce a virtual, upright, reduced image, whatever the object's distance.
The thin lens equation, 1/f = 1/do + 1/di, plus the magnification equation, m = -(di / do), cover every convex lens case the HESI asks about.