Question

An object is placed at a distance of 4 cm in front of a pinhole camera of length 12 cm. Find the magnification of the impression.​

Answer 1

Answer:

Let AB be the height of the object. Let M be the midpoint of AB. Let CD be the height of the image. Let N be the midpoint of CD. Let O be the pinhole. Align the points M, O, & N. MO = 50 cm and NO = 10 cm. MB = 20/2 = 10 cm. Triangles BMO and CNO are similar because <BOM = <CON (vertically opposite) and <M = <N = 90. The sides of similar triangles are proportional. Then: CN / BM = NO / MO →

CN / 10 = 10 / 50 → CN = 2 cm. The height of the image therefore is 4 cm.