An object is placed 30 cm from a converging lens with a focal length of 15 cm. Where is the image formed?
A10 cm on same side
B30 cm on opposite side
C15 cm on same side
DAt infinity
Explanation
📌 1/d_o + 1/d_i = 1/f. 1/30 + 1/d_i = 1/15. 1/d_i = 1/15 − 1/30 = 2/30 − 1/30 = 1/30. So d_i = 30 cm (real image, opposite side). Distractor A: sign error; C: reported f; D: only when object at f.