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ANEK [815]
3 years ago
12

A 35-year-old patent clerk needs glasses of 50-cm focal length to read patent applications that he holds 25 cm from his eyes. Fi

ve years later, he notices that while wearing the same glasses, he has to hold the patent applications 40 cm from his eyes to see them clearly.
What should be the focal length of new glasses so that he can read again at 25cm?
Physics
1 answer:
Natali5045456 [20]3 years ago
6 0

Answer:

28.57 cm

Explanation:

We are given that

Focal length,f=50 cm

Distance of application from his eyes,s=40 cm

\frac{1}{s}+\frac{1}{s'}=\frac{1}{f}

\frac{1}{40}+\frac{1}{s'}=\frac{1}{50}

\frac{1}{s'}=\frac{1}{50}-\frac{1}{40}=\frac{4-5}{200}

s'=\frac{200}{-1}=-200 cm

s=25 cm

Substitute the values

\frac{1}{25}-\frac{1}{200}=\frac{1}{f'}

\frac{8-1}{200}=\frac{1}{f'}

\frac{1}{f'}=\frac{7}{200}

f'=\frac{200}{7}=28.57 cm

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2 years ago
A 360-nm thick oil film floats on the surface of a pool of water. the indices of refraction of the oil and the water are 1.5 and
jenyasd209 [6]
The correct answer is 432, and 720.
The thickness of a film is t= 360nm
the refractive index of oil n₀t = (m +1/2) λ
For m =0
λ = 4n₀t
= 4(1.50)(360)
= 2160nm
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λ = 4n₀t
= 4(1.50)(360)/3
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7 0
3 years ago
How does a substitution mutation affect a cell?
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6 0
3 years ago
a box is at rest on a ground. An unbalance force acts on the box causes it to start. The box moves 10 meters in 2 seconds and th
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5 0
2 years ago
Thomas and John are carrying a 43kg cylinder head on a 510cm X 510mm board. The cylinder head with dimensions of 43cm X 250mm li
tatyana61 [14]

John carry the heaviest load.

<h3>How to find out who is carrying the heavy load?</h3>

Write down given data from questions:

Board=510cm X 510mm.

Cylinder head with dimensions=43cm X 250mm.

Cylinder lies across the board 210cm from john.

Find out: Who is carry the heaviest load?​

Calculation:

We assume that mass of cylinder head = x kg

Then weight=x x 9*81

                 W=9.81x  Newton.

Weight per unit length= Weight/Total leanth

Weight per unit length= 9.81x/43

(w/l)=0.23x N/cm

From equation contition: (F_{J} +F_{T} =9.81x n)

F_{T} (510)=9.81x  (210+21.5)

F_{T} (510)=9.81 x (231.5)

F_{T} =4.452x N.

F_{J} =9.81x-4.452x

F_{J} =5.358 xN

Therefore F_{J} \geq F_{T}

To learn more about mass per unit length, refer to:

brainly.com/question/24180692

#SPJ9

4 0
1 year ago
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