複選題60. For a bi-concave thin lens, the radii of curvature are 10 and 20 cm. If an object is placed 15 cm in front of the mirror, what is the magnification of the image and is it a real or virtual? Upright or inverted? (thin lens’ equation: 1/p+1/q = (n−1)(1/R1−1/R2), the refractive index of glass is 1.5). (AB) 9.72 cm (virtual behind mirror) and M = 0.64, inverted (AC) 11.64 cm (virtual behind mirror) and M = 0.58, inverted (AD) 10.91 cm (virtual in front mirror) and M = 0.73, upright (AE) 8.69 cm (real in front mirror) and M = 0.25, inverted (BC) 12.45 cm (virtual behind mirror) and M = 0.53, upright (BD)一律送分