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17.1 Maple Help

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17.1 Maple Help Empty 17.1 Maple Help

Post  kibakun Mon Feb 09, 2009 8:06 pm


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17.1 Maple Help Empty Questions 1, 2, 3 , 4

Post  kibakun Mon Feb 09, 2009 8:10 pm

1. I = q/t
Conventional direction of the current runs opposite to electrons

2. V = R * I
In the direction of conventional the voltage drops

3. Vab = Ir

Terminal is always less than nominal

4. R = p * L/A or p = RA / L

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Post  helpplss Mon Feb 09, 2009 9:07 pm

how do you convert mA to A?

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Post  guest_01 Mon Feb 09, 2009 9:13 pm

to convert mA to A divide by 1000

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Post  excuze m Mon Feb 09, 2009 9:48 pm

A 231.1 mA current flows through a 2.04 k resistor.

im put the mA into A's but why does it say 2.04 k ? do you have to do something with that or you just multiplying? its not working for me

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Post  kibakun Mon Feb 09, 2009 10:42 pm

you dont have to convert k it doesnt mean anything... for 2 and 3 one of them you have to convert from mA and the other you don't have to... just play around with it alittle.

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Post  Guest01 Tue Feb 10, 2009 4:48 am

I'd just like to give what I believe is a helpful tip, especially for questions like Question 2.

Besides remembering Ohm's Law as V=IR (this way I pronounce it out: Vurr Laughing), there's a handy little chart to remember the equation and help you find what you are looking for.
17.1 Maple Help IntroD2

When you need to find the part you are looking for, just cover the letter and read out the new equation.

For instance to find Voltage V. Block out the V and you have the equation to figure it out which is now I*R
17.1 Maple Help IntroD3

Same goes for the current I just place your finger over the I in the chart and you then have V/R
17.1 Maple Help IntroD4

There are also a few for calculating with Power and Energy, if it's ever needed.
The formula for Energy being the same as for Voltage E=I*R. Power is P=I2*R.

Hope that helps!

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17.1 Maple Help Empty 17.1 #4

Post  frustrat Tue Feb 10, 2009 11:16 am

can somebody post a detailed way to do number 4 i just can't seem to get it
thanks!

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Post  pleaseee Tue Feb 10, 2009 1:39 pm

yo i still cant get #2 for some reason. I took my mA and divided by 1000 which made it a decimal. Then i did my resistance/amps and i get another decimal but its still not working. what am i doing wrong?

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17.1 Maple Help Empty #2

Post  :) Tue Feb 10, 2009 1:55 pm

i'm not getting this either, i converted the mA to A by dividing by 100 then multiplied that with given kI. (tried converting kI to I as well by either multiplying by 1000 or dividing by)

i know the answer is negative though

:)
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17.1 Maple Help Empty #4

Post  guest768 Tue Feb 10, 2009 3:11 pm

for number 4:

A 356.8 mA current flows through a 52.89 cm long wire with a 0.5 V potential difference across it. The wire is cylindrically shaped and has a radius of with 0.827 mm. What is the resistivity of the wire material (see sheet 13,16) ? Indicate with a positive (negative) sign whether the resistivity depends (does not depend) on the cross sectional shape of the wire.

use p=RA/L
p= resistivity of material
R= resistance
A= area
L= length

R=V/I so .5V/.3568A = 1.40135 ohm
A=pi*r^2 = pi(.000827^2)= 2.149*10^-6

then just plug everything in:
p=RA/L
p= (1.40135(2.149*10^-6))/.5289
p=-5.69389*10^6

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Post  guest1 Tue Feb 10, 2009 4:58 pm

can someone please further explain question 2 and 3!!!

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17.1 Maple Help Empty Q2 and Q3

Post  sjames Tue Feb 10, 2009 6:08 pm

I am also having trouble with Q2 and Q3 plz help?

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17.1 Maple Help Empty #2&3

Post  super mo Tue Feb 10, 2009 6:13 pm

V=R*I
R=4.212
I=221.4mA
answer is neg 932.537 do not convert
I just got #3
r=(E-V_ab)/I
E=2.9
V_ab=1.817
I=197.7/1000
So....r=(2.9-1.87)/.1977
answer +5.478
hope this helps
PS One BIG fat raspberry for the joke about using this site is considered cheating Evil or Very Mad

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Post  hmmm Tue Feb 10, 2009 6:47 pm

why dont you convert?

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Post  super mo Tue Feb 10, 2009 6:57 pm

I am not sure. I gotta go to a class good luck!

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Post  guest1 Tue Feb 10, 2009 8:01 pm

so basically for question 3

subtract the two voltages given and divide it by the current thats given that u converted (meaning mA to A by dividing by 1000)
answer is positive

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17.1 Maple Help Empty questions

Post  kibakun Tue Feb 10, 2009 9:47 pm

Dude at least try the questions before you come to the blog for help. Some of these are so easy it takes like 5 min to work around.

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17.1 Maple Help Empty Question 1

Post  Guest911 Tue Feb 10, 2009 10:54 pm

A current of 2.601 A flows through a conducting wire. How much charge passes through it in 3.151 hours (see sheet 2,4,14) ? Indicate with a positive (negative) sign whether the coventional direction of the current is in the (opposite to the) direction of the moving electrons.

How do i do this? i know it maybe easy for most people, but i can't seem to understand it. I tried using the equation and no good. I also looked at the cd and i am still not getting it. You have to convert hours to seconds right?

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17.1 Maple Help Empty 1

Post  maria Tue Feb 10, 2009 11:42 pm

I AM STILL NOT GETTING #1, PLZ HELP Crying or Very sad

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17.1 Maple Help Empty #1

Post  #1 Wed Feb 11, 2009 12:13 am

can someone help us with #1

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Post  J Wed Feb 11, 2009 12:24 am

#1 is simply a rearrangement of the formula I = q/t to get q, make sure you convert hours to seconds.

Does anyone know why we convert the mA to A in #3 but not #2???

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17.1 Maple Help Empty Question 1

Post  Guest091 Wed Feb 11, 2009 12:59 am

for question 1 what i did was i took my 2.101 A divided that by 3.151 hours well i converted to seconds....so it came to be 11343.6 seconds...so i did 2.101/11343.6 and it gives me the wrong answer still

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Post  Guest01 Wed Feb 11, 2009 1:31 am

miliamperes (mA) is just a thousandth of an ampere (A). This is no different then describing the relationship between milimeters and meters. Same shit as last semester.

To convert mA into A divide mA by 1000 (or multiply by 0.001).

You will need to convert your Ohms as well, from kiliohms to ohms. These conversions will bring everything to S.I. Units.
Simple stuff, I hope this will be the last explanation of it.

For Question 1 you will need to convert hours into seconds. Multiply hours and 3600 (that is 60*60 - converting hours into minutes; the first 60, then minutes into seconds; the second 60)

Again shit we have done in the past fall.

Rearrange the equation to suit your needs.

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17.1 Maple Help Empty Guest01

Post  play nic Wed Feb 11, 2009 1:19 pm

I don't know if this is a mis communication or if you are indeed being an asshole. It may seem super easy for you to see some of these things, but there are students in this class believe it or not, that are still trying to understand this stuff. Yes you will have lazy students here and there, but there are students who really don't understand number 2/1. So if you think students asking questions is annoying then dont freaking use the site. Otherwise stop being an asshole explaining the answers like you were some self righteous ass.

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