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kakasveta [241]
3 years ago
12

Example: What power of spectacle lens is needed to correct the vision of a nearsighted person

Physics
1 answer:
Aleksandr [31]3 years ago
4 0
<h3>Concave or diverging lens is needed correct the vision of a nearsighted person  whose far point is 30.0 cm</h3>

<em><u>Solution:</u></em>

Nearsighted person will not be able to see the distant objects clearly

Now, we want the near sighted person to see the distant objects clearly

<em><u>The lens equation is given as:</u></em>

P = \frac{1}{d_o} + \frac{1}{d_i}

For distant vision, d_0 = \infty

d_i = image\ distance\\\\d_0 = lens\ to\ retina\ distance

The image of 30 cm from eye will be 28.5 cm to left of spectacle lens

Therefore,

d_i = -28.5\ cm = 0.285\ meter

From lens equation,

P = \frac{1}{ \infty } + \frac{1}{-0.285\ meter}\\\\P = 0 - 3.51 \\\\P = -3.51\ diopter

The negative power -3.51 D denotes that a concave or diverging lens is needed

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Brilliant_brown [7]

Answer:

Thermal Power = 460W

Explanation:

From Stephan-Boltzmann Law Formula;

P = єσT⁴A

Where,

P = Radiation energy

σ = Stefan-Boltzmann Constant

T = absolute temperature in Kelvin

є = Emissivity of the material.

A=Area of the emitting body

Now, σ = 5.67 x 10^(-8)

є = 0.6

Temperature = 30°C and coverting to kelvin = 30 + 273 = 303K

Area ; since we are to consider the sides of the human body as 2m and 0.8m,thus area = 2 x 0.8 = 1.6

Thus thermal power = 0.6 x 5.67 x 10^(-8) x303⁴ x 1.6 = 458. 8W

Normally, we approximate to the nearest 10W. Thus, thermal power is approximately 460W

4 0
3 years ago
A car traveled 176 miles on 6.4 gallons of fuel the car averaged how many miles per gallon
earnstyle [38]
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2 years ago
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Rudiy27
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3 years ago
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10) Two students want to use a 12-meter long rope to create standing waves. They first measure the speed at which a single wave
zhannawk [14.2K]

Answer:

To create a second harmonic the rope must vibrate at the frequency of 3 Hz

Explanation:

First we find the fundamental frequency of the rope. The fundamental frequency is the frequency of the rope when it vibrates in only 1 loop. Therefore,

f₁ = v/2L

where,

v = speed of wave = 36 m/s

L = Length of rope = 12 m

f₁ = fundamental frequency

Therefore,

f₁ = (36 m/s)/2(12 m)

f₁ = 1.5 Hz

Now the frequency of nth harmonic is given in general, as:

fn = nf₁

where,

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f₁ = fundamental frequency = 1.5 Hz

Therefore,

f₂ = (2)(1.5 Hz)

<u>f₂ = 3 Hz</u>

5 0
3 years ago
When a quantity of monatomic ideal gas expands at a constant pressure of 4.00×104pa, the volume of the gas increases from 2.00×1
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Yes that is correct. We know this because 4.00 x 10 4 Pa is constant. If you have 2.00×10−3m3 then you do the following: (2.00×10^−3)(4.00×10^<span> 4) = </span>8.00×10^−3. That is how you get your answer
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