If he does not use the lenses, his near point will be 66.7 cm. For him to read a material at 50 cm, he has to use a lens of 2.0D.
<h3>What is the near point?</h3>
The near point is the nearest area which a person can see or have distinct vision. The focal length of the lens is f = 100/2.5 = 40cm
Then;
1/40 = -1/v + 1/25
1/v = 1/25 - 1/40
v = 66.7 cm
Also, for the purpose of reading at 50 cm
1/f = -1/50 + 1/25
1/f = 1/25 - 1/50
f = 50cm
The power of this lens is;
100/50 cm = 2 D
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Answer:
n = 5 approx
Explanation:
If v be the velocity before the contact with the ground and v₁ be the velocity of bouncing back
= e ( coefficient of restitution ) =
and
h₁ is height up-to which the ball bounces back after first bounce.
From the two equations we can write that
So on
= .00396
Taking log on both sides
- n / 2 = log .00396
n / 2 = 2.4
n = 5 approx
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Answer:
<em>Radiation is energy that comes from a source and travels through space and may be able to penetrate various materials. Light, radio, and microwaves are types of radiation that are called nonionizing.</em>
Explanation: