A plastic lens is made with material with index of refraction n=1.4. If the fron
ID: 2304915 • Letter: A
Question
A plastic lens is made with material with index of refraction n=1.4. If the front lens is ground to a radius of 1.3 m and the rear lens ground to a radius of -0.9 m, what is the refractive power of the lens?
-0.14 diopters
0.75 diopters
1.5 diopters
-0.48 diopters
A plastic lens is made with material with index of refraction n=1.4. If the front lens is ground to a radius of 1.3 m and the rear lens ground to a radius of -0.9 m, what is the focal length of the lens?
1.5 m
-7.3 m
0.75 m
-0.14 m
A 1.2 cm figurine is placed 0.8 m in front of the lens in the previous problem. Where will the image be?
1.7 m from the lens on the opposite side from the object.
1.7 m from the lens on the same side as the object.
0.52 m from the lens on the same side as the object.
0.52 m from the lens on the opposite side from the object.
A 1.2 cm figurine is placed 0.8 m in front of the lens in the previous problem. Will the image be upright or inverted?
There will be no image.
Upright
More information is required to answer this question.
Inverted
A 1.2 cm figurine is placed 0.8 m in front of the lens in the previous problem. What will the height of the image be? You may take the absolute value of the image height.
2.6 cm
2.1 cm
1.2 cm
8.4 cm
a.-0.14 diopters
b.0.75 diopters
c.1.5 diopters
d.-0.48 diopters
Explanation / Answer
from Lens maker's formula,
1/f = (n - 1)[1/R1 - 1/R2]
and P = 1/f
P = (1.4 - 1)[1/1.3 - 1/0.9]
P = - 0.14 D .......Ans(A)
----------------------
f = 1/P = 1/(-0.14) = - 7.3 m
Ans(b)
-------------------------
1/f = 1/p + 1/q
1/-7.3 = 1/0.8 + 1/q
q = - 0.72 m
0.72 m from the lens on the same side
----------------
m = -q /p = 0.90
m is positive so image will be upright
---------------------
hi = m ho = 0.90 x 1.2 = 1.1 cm
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.