MAGNIFYING GLASS: A magnifying glass is formed from a single double convex (conv

Question

MAGNIFYING GLASS: A magnifying glass is formed from a single double convex (converging) lens with a focal length of f = + 12.0 cm . The lens, with focal points labeled by F, is shown in the schematic (figure 1) next page. It could be the model for a Bart passenger's reading glasses while she scans the afternoon's news headlines. The distance |di| is the distance between one of the lens's and the virtual IMAGE of the news story of the Sharks victory she wants to read about. Note: do f in this problem. Figure 1 applies to more general situations like part (a) and also to a special condition like part (b), (c) and (d) with certain adjustments of diagram. Figure 1 also shows the unaided eye viewing the object a distance 25 cm away. Note that N = near point distance = 25 cm. Suppose d0 = 10.0 cm. Compute di and find the linear magnification m = -di/d0. Now change the problem for a special situation in parts (b), (c ) and (d). Assume d0 = f for these next parts: In this case, we know the lens forms a virtual image at di = . What is the angular magnification M = theta'/theta? Suppose the object is an insect 2.50 mm in length. What is angle theta in the formula for the angular magnification M? What is theta' in the formula for the angular magnification M?

Explanation / Answer

Part A)

Apply 1/f = 1/p + 1/q

1/12 = 1/10 + 1/q

q = -60 cm

M = -(-60)/10

M = 6

Part B)

m = 25/f

m = 25/12

m = 2.5

Part C)

(Theta) = 2.5/120

Theta = .0208 radians (that is 1.19 degrees)

Part D)

2.5 = (Theta')/.0208

Theta' = .0521 radians (that is 2.98 degrees)

Related Questions

Navigate

• Browse (All)
• Browse M
• Subjects

---

---

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