A converging lens has a focal length of 29.9 cm. (a) Locate the object if a real

Question

A converging lens has a focal length of 29.9 cm. (a) Locate the object if a real image is located at a distance from the lens of 119.6 cm. distance .......... cm (b) Locate the object if a virtual image is located at a distance from the lens of -59.8 cm. distance ......... cm (c) Locate the object if a virtual image is located at a distance from the lens of -119.6 cm. distance ........... cm

Explanation / Answer

do = u and di = v = 2u So f = 2u/3-----------(1) In second case do = u1 and di = 3u1 So f = 3u1 / 4 ------------(2) ===> 3u1 / 4 = 2u / 3 Or u1 / u = 8/9 ----------(3) Given v1 - v = 89.7 cm-------------(4) Also v1/u1 = 3 and v/u = 2--------------------(5) So 2v1 /u1 = 6 = 3v / u ====> 2v1/3v = u1/ u or v1 / v = 3u1 / 2u v1 - v = v * (3u1 - 2u) / 2u From 4 and 5, 3u1 - 2u = 89.7 cm From u1 = 8u/9 So solving for u, we get u = 3*89.7 / 2 = 134.6 cm So u1 = 8* 134.6 / 9 = 119.6 cm So the object has been moved towards the mirror through a distance 134.6 - 119.6 = 15 cm.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.