#1
I've recently become interested in silk-screening, and yesterday I finished gathering the necessary materials. Part of the process involves exposing photographic emulsion with a lightbulb. The book my kit came with has exposure times for 150 and 250 watt bulbs, but my bulb is 200w. I know I need to graph an asymptote to find the proper exposure time, but I can't find my graphing calculator and even if I could I wouldn't know where to begin, as I haven't taken any math classes for almost three years. SO, UG, my question for you is:

If a 150 watt bulb requires 45 minutes of exposure time, and a 250 watt bulb requires only 10 minutes, how long should the exposure be with a 200 watt bulb?
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#3
I think we need more values as I don't think it will be a simple graph, as 300W would need 22 minutes if this graph was straight.

Or I calculated incorrectly.
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#7
I just realised how unbelievably shit at maths I am.
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#8
Quote by Simsimius
I think we need more values as I don't think it will be a simple graph, as 300W would need 22 minutes if this graph was straight.

Or I calculated incorrectly.


I know it's an asymptote. I forget the skeletal equation for them, but they're the curves that get infinitely high as they approach the Y axis and infinitely low as they approach the X axis.
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#9
Quote by icaneatcatfood
17.5 lololol


+1.
I did this one with my brain still on hibernate mode.
#10
Quote by kdcisgod
+1.
I did this one with my brain still on hibernate mode.
It's not linear, it's a rational equation or something like that. I took trigonometry this year and I already forget how to do all that stuff

TS, I don't believe you can figure out exactly, since you would only have two given points on the graph. You need three. I think.
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Last edited by food1010 at Jul 19, 2009,
#11
Quote by Simsimius
I think we need more values as I don't think it will be a simple graph, as 300W would need 22 minutes if this graph was straight.

Or I calculated incorrectly.

Well even if the graph was straight seeing as he said a 250w takes 10 minutes...

...
███████
███████████
██████████████
███████████████
█████████████
███████████████
███████████
███████

#12
Quote by kdcisgod
+1.
I did this one with my brain still on hibernate mode.


Ferreal? Many thanks if this works.
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#13
here's a novel idea: go out and spend under 5 bucks on a bulb of the correct wattage

/thread
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#14
based on what you've got there's no way to find an answer that ends up being an asymptote, with 2 points its only a straight line. if we had more than 2 points then you could start showing a curve. as it is, you need more info.
#15
Quote by poopsmith666
here's a novel idea: go out and spend under 5 bucks on a bulb of the correct wattage

/thread



This.


Due to the non-linearity of the ratio; you will need at least one more point for comparison. Otherwise, you would need the specific heat of the material and a number of other physical constants to calculate how long it takes to reach the proper temperature and dampness.

It's all possible, but you need to give us more to work with.

(Credentials: Bachelor in Mathematics, Bachelor in Physics)
#16
Quote by poopsmith666
here's a novel idea: go out and spend under 5 bucks on a bulb of the correct wattage

/thread


Maybe you should consider the possibility that I looked for the right bulb since I had to go to the hardware store to buy the bulb I ended up with before being a smartass.
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#18
Quote by ZanasCross
This.


Due to the non-linearity of the ratio; you will need at least one more point for comparison. Otherwise, you would need the specific heat of the material and a number of other physical constants to calculate how long it takes to reach the proper temperature and dampness.

It's all possible, but you need to give us more to work with.

(Credentials: Bachelor in Mathematics, Bachelor in Physics)
Yay, I was right
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#21
Ugh, forget it. I bought the 200w bulb to save 20 min or so, but I could have done a screen and a half in the time I've been trying to figure this out with the 150. Thanks anyway, everyone. And ZanasCross, If I find out more about the setup, I might PM you for the answer.
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#22
I don't think the graph is linear, much the same as one Pizza Pocket takes 1:30 to cook in a microwave, while the second one only takes an additional 30 seconds.

(I think.)No, but I'm badass at maths.Technically that is the correct way to say it, as it's short for mathematics instead of mathematic, but both are widely accepted.
Last edited by Pat_s1t at Jul 19, 2009,
#23
Quote by VoodooChild15
Maybe you should consider the possibility that I looked for the right bulb since I had to go to the hardware store to buy the bulb I ended up with before being a smartass.

chill man.

if you read your first post again, all it says is "the book has exposure times for 150 and 250, but my bulb is 200" How did you expect me to glean the information that you went to the hardware store to get it, and that you didn't just have them at your house already, but decided at the last minute to get 200 instead of 150 to save time?

don't get so defensive
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