inverted images real ref name geoptics lenses suffer aberrations distort images ''monochromatic aberrations'' occur geometry lens perfectly direct rays object point single point image chromatic aberration occurs index refraction lens varies wavelength light ref name geoptics images black letters thin convex lens focal length ''f'' nbsp shown red selected rays shown letters '''e''' '''i''' '''k''' blue green orange respectively note '''e''' ''f''
Natural science Physics Optics