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3 years ago

How does the distance from an eye chart affect the number of letters that are recognized on a line

Physics

2 answers:

luda_lava [24]3 years ago

8 0

Explanation:

Distance from the eye chart are used to find defect in the in the eye sights of a patient. If one cannot see far off things, that means he is near sighted. So if he goes away from the eye chart and try to see the letters in the chart, he will see blur image of the letters.

And if one is far sighted he cannot see the near by things. If one comes closer to the chart and tries to read the letters then he will not be able to read those letters because he is far sighted.

Thus, in this way distance from the eye chart affect to recognize the letters present in the eye chart.

Nat2105 [25]3 years ago

3 0

Well, if you are nearsighted which means you can't see far, the father you are the more blurry it will be, resulting to you saying the wrong letter. This then shows the doctor that you can't see far away, nearsighted.

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List three examples of compounds and three examples of mixtures

sergij07 [2.7K]

Compounds:
hydrogen
methane
hydrochloric acid
mixtures:
salt and water
oil and water
sugar and hot water
(stuff in day to day life basically)

8 0

3 years ago

Calculate the ratio of the resistance of 12.0 m of aluminum wire 2.5 mm in diameter, to 30.0 m of copper wire 1.6 mm in diameter

alukav5142 [94]

Answer: 0.258

Explanation:

The resistance $R$ of a wire is calculated by the following formula:

$R=\rho\frac{l}{s}$ (1)

Where:

$\rho$ is the resistivity of the material the wire is made of. For aluminium is $\rho_{Al}=2.65(10)^{-8}m\Omega$ and for copper is $\rho_{Cu}=1.68(10)^{-8}m\Omega$

$l$ is the length of the wire, which in the case of aluminium is $l_{Al}=12m$ , and in the case of copper is $l_{Cu}=30m$

$s$ is the transversal area of the wire. In this case is a circumference for both wires, so we will use the formula of the area of the circumference:

$s=\pi{(\frac{d}{2})}^{2}$ (2) Where $d$ is the diameter of the circumference.

For aluminium wire the diameter is $d_{Al}=2.5mm=0.0025m$ and for copper is $d_{Cu}=1.6mm=0.0016m$

So, in this problem we have two transversal areas:

For aluminium:

$s_{Al}=\pi{(\frac{d_{AL}}{2})}^{2}=\pi{(\frac{0.0025m}{2})}^{2}$

$s_{Al}=0.000004908m^{2}$ (3)

For copper:

$s_{Cu}=\pi{\frac{(d_{Cu}}{2})}^{2}=\pi{(\frac{0.0016m}{2})}^{2}$

$s_{Cu}=0.00000201m^{2}$ (4)

Now we have to calculate the resistance for each wire:

Aluminium wire:

$R_{Al}=2.65(10)^{-8}m\Omega\frac{12m}{0.000004908m^{2}}$ (5)

$R_{Al}=0.0647\Omega$ (6) Resistance of aluminium wire

Copper wire:

$R_{Cu}=1.68(10)^{-8}m\Omega\frac{30m}{0.00000201m^{2}}$ (6)

$R_{Cu}=0.250\Omega$ (7) Resistance of copper wire

At this point we are able to calculate the ratio of the resistance of both wires:

$Ratio=\frac{R_{Al}}{R_{Cu}}$ (8)

$\frac{R_{Al}}{R_{Cu}}=\frac{0.0647\Omega}{0.250\Omega}$ (9)

Finally:

$\frac{R_{Al}}{R_{Cu}}=0.258$ This is the ratio

3 0

3 years ago

Planet Tatoone is about 1.7 AU from its Sun. Approximately how long will it take for light to travel from the Sun to Tatoone in

Radda [10]

Answer:

The value is $t = 14.129 \ minutes$

Explanation:

From the question we are told that

The distance of planet Tatoone is $d = 1.7 \ AU = 1.7 *1.496* 10^{11}=2.543*10^{11} \ m$

The speed of light is $c = 3.0*10^{8} \ m/ s$

Generally the time taken is mathematically represented as

$t = \frac{d}{c}$

=> $t = \frac{2.543*10^{11}}{3.0*10^{8} }$

=> $t = 847.7 \ s$

Now converting to minutes

$t = \frac{847.7}{60}$

=> $t = 14.129 \ minutes$

8 0

3 years ago

Air resistance is an example of what type of friction?

Sav [38]

Well, Air resistance is a special type of friction (you cannot classify it in other categories). That force of air-resistance is often observed to oppose the motion of the object,( like every other frictional forces)

Hope this helps!

4 0

4 years ago

What percentage does each parent contribute to a child's genotype?

bearhunter [10]

Each parent contribute 50 percent. A person have 46 genes and 23 comes from the mother and 23 comes from the father

5 0

3 years ago

Read 2 more answers