A 5.09-mm-high firefly sits on the axis of, and 10.3 cm in front of, the thin le

Question

A 5.09-mm-high firefly sits on the axis of, and 10.3 cm in front of, the thin lens A, whose focal length is 5.71 cm. Behind lens A there is another thin lens, lens B, with focal length 22.5 cm. The two lenses share a common axis and are 62.3 cm apart. Is the image of the firefly that lens B forms real or virtual?

How far from lens B is this image located (expressed as a positive number)? ___cm

What is the height of this image (as a positive number)? ___mm

Is this image upright or inverted with respect to the firefly?

Explanation / Answer

Part A)
For the first lens

1/f = 1/p + 1/q

1/5.71 = 1/10.3 + 1/q

q = 12.8 cm

Since the lenses are 62.3 cm apart, this image is the object for the second lens and 62.3 - 12.8 = 49.5 cm in front of it

Then for the second lens

1/22.5 = 1/49.5 + 1/q

q = 41.3 cm

Part B)

The magnification is -q/p times -q/p

That is -12.8/10.3 times - 41.3/49.5

M = 1.04

h' = (1.04)(5.09) = 5.28 mm

Part C)

Since the overall magnification is positive, the image is upright

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

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