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ipn [44]
3 years ago
10

Where is the near point of an normal eye when accidentally wear a contact lens with a power of +2.0 diopters?

Physics
1 answer:
Lerok [7]3 years ago
7 0

Answer:

The near point of an eye with power of +2 dopters, u' = - 50 cm

Given:

Power of a contact lens, P = +2.0 diopters

Solution:

To calculate the near point, we need to find the focal length of the lens which is given by:

Power, P = \frac{1}{f}

where

f = focal length

Thus

f = \frac{1}{P}

f = \frac{1}{2} = + 0.5 m

The near point of the eye is the point distant such that the image formed at this point can be seen clearly by the eye.

Now, by using lens maker formula:

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

where

u = object distance = 25 cm = 0.25 m = near point of a normal eye

u' = image distance

Now,

\frac{1}{u'} = \frac{1}{f} - \frac{1}{u}

\frac{1}{u'} = \frac{1}{0.5} - \frac{1}{0.25}

\frac{1}{u'} = \frac{1}{f} - \frac{1}{u}

Solving the above eqn, we get:

u' = - 0.5 m = - 50 cm

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3 years ago
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Suppose that a worker in Freedonia can produce either 6 units of corn or 2 units of wheat per year, and a worker in Sylvania can
Salsk061 [2.6K]

Answer:

a 30 units of corn and 30 units of wheat.

Explanation:

Initially freedonia has 5 workers producing 30 units of of corn (6 units per worker) and another 5 workers producing 10 units of wheat (2 units per worker)

With the trade agreed between the two countries Freedonia can have all of it's 10 workers producing corn, thereby producing 60 units of corn

30 of these are traded for 30 units of wheat therefore allowing the country to consume 30 units of each product.

8 0
3 years ago
In an extrasolar planetary system containing a single planet, the parent star is measured to move about its center of mass every
Mademuasel [1]

Answer:

Orbital Time Period is 24 years

Explanation:

This can be explained by the definition of time period.

Time period can be defined as the time taken by an object to complete one cycle, here, time taken to complete one revolution.

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Therefore, the time taken by the parent star to move about its mass center is the orbital time period that is 24 years.

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Explain the relationship between the earth's crust and the earth's ocean sizes.
valina [46]

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hope it helps

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2 years ago
Consider a heat pump that operates on the reversed Carnot cycle with R-134a as the working fluid executed under the saturation d
Schach [20]

Answer:

Work out = 28.27 kJ/kg

Explanation:

For R-134a, from the saturated tables at 800 kPa, we get

h_{fg} = 171.82 kJ/kg

Therefore, at saturation pressure 140 kPa, saturation temperature is

T_{L} = -18.77°C = 254.23 K

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T_{H} = 31.31°C = 304.31 K

Now heat rejected will be same as enthalpy during vaporization since heat is rejected from saturated vapour state to saturated liquid state.

Thus, q_{reject} = h_{fg} = 171.82 kJ/kg

We know COP of heat pump

COP = \frac{T_{H}}{T_{H}-T_{L}}

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         = 6.076

Therefore, Work out put, W = \frac{q_{reject}}{COP}

                                              = 171.82 / 6.076

                                              = 28.27 kJ/kg

8 0
3 years ago
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