# Physics As question (Help)

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YesterdaysDreams

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#1

jaichandak

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Kyx

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Onlineslayer

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Kyx

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jaichandak

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YesterdaysDreams

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#7

as i don't get it

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Username002

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#8

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#8

5) R=rho*a/l = rho*pi*r^2/l

d=2r

2d=4r

R=rho*pi*(4r)^2/l compared to R=rho*pi*(2r)^2/l

6)

1/R total = 1/r1 + 1/r2

r1= 4+4

r2= 4+4

d=2r

2d=4r

R=rho*pi*(4r)^2/l compared to R=rho*pi*(2r)^2/l

6)

1/R total = 1/r1 + 1/r2

r1= 4+4

r2= 4+4

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Onlineslayer

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#9

(Original post by

5) R=rho*a/l = rho*pi*r^2/l

d=2r

2d=4r

R=rho*pi*(4r)^2/l compared to R=rho*pi*(2r)^2/l

6)

1/R total = 1/r1 + 1/r2

r1= 4+4

r2= 4+4

**Username002**)5) R=rho*a/l = rho*pi*r^2/l

d=2r

2d=4r

R=rho*pi*(4r)^2/l compared to R=rho*pi*(2r)^2/l

6)

1/R total = 1/r1 + 1/r2

r1= 4+4

r2= 4+4

Resistance is always proportional to length, not Area.

R = rho L/A

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Jpw1097

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#10

5. R = ρL/A

Therefore R α 1/A (that is, resistance is inversely proportional to the cross-sectional area) provided that the length and resistivity of the wire remain constant.

Area of a wire = πr

^{2}or A = πd

^{2}/4.

Therefore, if the diameter of the wire is doubled the area will increase by a factor of 4. Since R α 1/A, and area is 4 times greater, resistance must decrease by a factor of 4. Hence R

_{new}= 0.25R. Therefore the answer is A.

6. You have to find the total resistance of the resistors in series first.

Remember, for resistors in series R

_{total}= R

_{1}+ R

_{2}+ ... + R

_{n}

So to find the resistance of the two 4Ω resistors in parallel you just simply add the individual resistance of each resistor.

R

_{total}= 4Ω + 4Ω = 8Ω

Now, you can think of the circuit as two 8Ω resistors in parallel. Remember, for resistors in parallel 1/R

_{total}= 1/R

_{1}+ 1/R

_{2}+ ... + 1/R

_{n}

So to find the resistance of the two 8Ω resistors in parallel you have to use the formula

1/R

_{total}= 1/8 + 1/8

1/R

_{total}= 2/8 = 1/4

So to find R

_{total}you just take the reciprocal of both sides, so R

_{total}= 4Ω.

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Absent Agent

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#11

(Original post by

Pls correct your first equation.

Resistance is always proportional to length, not Area.

R = rho L/A

**Onlineslayer**)Pls correct your first equation.

Resistance is always proportional to length, not Area.

R = rho L/A

**didn't**have the courage to help.

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uberteknik

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#12

**Onlineslayer**)

Pls correct your first equation.

__Resistance is always proportional to length, not Area.__

R = rho L/A

Resistance is proportional to

__both__length and area.

If the length increases the resistance also increases.

If the area increases, the resistance falls.

Because the cross sectional area of the wire is a square function of the diameter, if the diameter doubles, the c.s.a. increases by a factor of 4.

Hence for the same length, the resistance must fall by a factor of 4.

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YesterdaysDreams

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Onlineslayer

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#14

(Original post by

Rookie mistake.

Resistance is proportional to

If the length increases the resistance also increases.

If the area increases, the resistance falls.

Because the cross sectional area of the wire is a square function of the diameter, if the diameter doubles, the c.s.a. increases by a factor of 4.

Hence for the same length, the resistance must fall by a factor of 4.

**uberteknik**)Rookie mistake.

Resistance is proportional to

__both__length and area.If the length increases the resistance also increases.

If the area increases, the resistance falls.

Because the cross sectional area of the wire is a square function of the diameter, if the diameter doubles, the c.s.a. increases by a factor of 4.

Hence for the same length, the resistance must fall by a factor of 4.

Be that as it may, the correct formulae speaks for itself and I'm sure the author of the incorrect formulae got my message square and clear.

And FYI, "rookie" mistakes are for a category of people.

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#15

(Original post by

You don't have the right to criticise when you

**Absent Agent**)You don't have the right to criticise when you

**didn't**have the courage to help.And when did correcting critical mistakes become "criticism"?

If you had the "courage" to scan through, you would have seen my earlier contribution. But of course, you decided to only attack as usual.

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Absent Agent

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#16

(Original post by

and you are?

And

**Onlineslayer**)and you are?

And

**when**did correcting critical mistakes become "criticism"?
If you had the "courage" to scan through, you would have seen my earlier contribution. But of course, you decided to only attack as usual.

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uberteknik

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#17

(Original post by

I don't understand your own definition of proportional. When the correlation is positive, we other say it is directly proportional, or we just say it is proportional. And when the correlation is negative, we categorically state that it is Inversely-proportional.

Be that as it may, the correct formulae speaks for itself and I'm sure the author of the incorrect formulae got my message square and clear.

And FYI, "rookie" mistakes are for a category of people.

**Onlineslayer**)I don't understand your own definition of proportional. When the correlation is positive, we other say it is directly proportional, or we just say it is proportional. And when the correlation is negative, we categorically state that it is Inversely-proportional.

Be that as it may, the correct formulae speaks for itself and I'm sure the author of the incorrect formulae got my message square and clear.

And FYI, "rookie" mistakes are for a category of people.

The message we get is you are up your own arse.

Good day.

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lerjj

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#18

**Onlineslayer**)

I don't understand your own definition of proportional. When the correlation is positive, we other say it is directly proportional, or we just say it is proportional. And when the correlation is negative, we categorically state that it is Inversely-proportional.

Be that as it may, the correct formulae speaks for itself and I'm sure the author of the incorrect formulae got my message square and clear.

And FYI, "rookie" mistakes are for a category of people.

Inversely proportional would usually mean . That's a hyperbola/reciprical relationship and is rarely what anyone means by "negative correlation".

As any good rookie knows, the more aloof your answer, the more likely it is to contain a mistkae

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#19

(Original post by

Just going to float by and state that your terminology is wrong - the word correlation is almost meaningless here. 'Proportional to' typically means is "Is equal to some constant times". This would probably include whatever you mean by a negative correlation (which I'm assuming you mean a negative slope).

Inversely proportional would usually mean . That's a hyperbola/reciprical relationship and is rarely what anyone means by "negative correlation".

As any good rookie knows, the more aloof your answer, the more likely it is to contain a mistkae

**lerjj**)Just going to float by and state that your terminology is wrong - the word correlation is almost meaningless here. 'Proportional to' typically means is "Is equal to some constant times". This would probably include whatever you mean by a negative correlation (which I'm assuming you mean a negative slope).

Inversely proportional would usually mean . That's a hyperbola/reciprical relationship and is rarely what anyone means by "negative correlation".

As any good rookie knows, the more aloof your answer, the more likely it is to contain a mistkae

"A negative correlation means that there is an inverse relationship between two variables - when one variable decreases, the other increases. The vice versa is a negative correlation too, in which one variable increases and the other decreases. These correlations are studied in statistics as a means of determining the relationship between two variables."

Read more at http://examples.yourdictionary.com/n...DgJL8bCDBA5.99

The dictionary is always there for us.

Y = -mx +c has a negative correlation relationship. Just as y = k/X does.

Just as in statistics, it's not about how straight the line is but the scattered plot of any points drawn.

Happy?

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lerjj

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#20

(Original post by

"A negative correlation means that there is an inverse relationship between two variables - when one variable decreases, the other increases. The vice versa is a negative correlation too, in which one variable increases and the other decreases. These correlations are studied in statistics as a means of determining the relationship between two variables."

Read more at http://examples.yourdictionary.com/n...DgJL8bCDBA5.99

The dictionary is always there for us.

Y = -mx +c has a negative correlation relationship. Just as y = k/X does.

Just as in statistics, it's not about how straight the line is but the scattered plot of any points drawn.

Happy?

**Onlineslayer**)"A negative correlation means that there is an inverse relationship between two variables - when one variable decreases, the other increases. The vice versa is a negative correlation too, in which one variable increases and the other decreases. These correlations are studied in statistics as a means of determining the relationship between two variables."

Read more at http://examples.yourdictionary.com/n...DgJL8bCDBA5.99

The dictionary is always there for us.

Y = -mx +c has a negative correlation relationship. Just as y = k/X does.

Just as in statistics, it's not about how straight the line is but the scattered plot of any points drawn.

Happy?

Moreover, nobody uses the term correlation if you're talking about a simple theoretical relationship - correlations are for experimental (statistical) data. Proportionality is a different concept, and trying to explain one in terms of the other won't work very well.

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