dn23
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#1
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#1
anyone been given this yet?
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aqfrenzy
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Yeah we've been given ours to do over Easter. I've done about 380 words (right upto end of circuit diagram so far), need to use the remaining 120 words carefully and maybe go over what I've already done too.

How are you gonna measure output of photocell?
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mysterioussme
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how are you doing it? i am really confused....don't know where to start?
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fblade
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(Original post by mysterioussme)
Yeah we've been given ours to do over Easter. I've done about 380 words (right upto end of circuit diagram so far), need to use the remaining 120 words carefully and maybe go over what I've already done too.

How are you gonna measure output of photocell?
how about the current?
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Coolraj
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(Original post by mysterioussme)
how are you doing it? i am really confused....don't know where to start?
I'm on the same boat man... hope to make some progress before the deadline... good luck to all!!!
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jiny_geni
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#6
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not really sure where to start???? should we have a look at how the automatic door actually works... then from that figures out how to plan the experiment????
can anyone tell me in details what we actually have to do????
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think_pink311
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yeah ive bin given this course work 2day.......i dnt have any idea were to start, ne1 gt ne ideas?:confused:
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flegghighsmells
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Planning Exercise

In this Planning Exercise, two marks are availble for the quality of written communication.

Automatic doors and barriers have detectors which determine wether it is safe to close the door or barrier. Often an infra-red source is used whose output is detected by a ohoto detector as show in Fig 1.1.


*Fig 1.1.* - A 2 part sliding door with a detector on 1 side and a photo detector on the other.



You are required to design a laboratory experiment to investigate how the output from a photocell depends on its distance from a point source of infra-red radiation.

You should pay particular attention to

(a) the procedure to be followed
(b) how the output of the photocell would be measured
(c) the range of distances that would be used
(d) the ranges of any measuring instruments used
(e) any relavant circuit diagrams
(f) any safety precautions you would take when carrying out the investigation
(g) particular features of the design that would ensure the accuracy and reliability of your results.

[14]
Quality of written communication [2]
[Total: 16]
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flegghighsmells
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#9
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What i am thinking is just wiring up the photodetector and emitter to a circuit, and simply measuring the p.d across it with a voltmeter. Use a ruler/metre rule to measure the distance from the detector and emitter and just by sliding it with your hand to see what the voltmeter reads!
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whirlwind
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#10
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#10
why shouldnt we use a photovoltaic photocell?
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think_pink311
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#11
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im not sure how to set up the circuit for this experiment, do i need a power supply? what else will i need apart from an ammeter and the photodetector cell?
pls help im so stuck!!! does anyone else find it hard??
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Subbacultcha
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basically, our teacher sat us down today in silence and made us write a rough draft, rlly rough, jus ideas, of our plan.

here's what i came up with:

simple circuit, with a voltmeter across the photocell, and a power supply supplying the infra-red emitter. wooh

then jus measuring the dist with a metre ruler.

so my two variables are the voltage o.p. and the distance.

my queries i have yet to sort - any advice?!

1) i will need to use a photovoltaic cell - seem ok?!

2) can we do prelim expts - i.e. can i see how many volts come out/how far away the i.r. thingy can get, so i know stuff like "the range of my measuring instruments" blah blah

3) what the hell are safety issues?! its only a teensy cell i shud think!!!

anyone have any HUUUGE probs p.m. me and i can try, or ask my mates - theyre all kinda clever at phys!

gud luck

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flegghighsmells
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#13
Safety issues:
Don't look into the beam?
Take caution if the experiment were to be run on a mains supply.
I can't think of any more off of the top of my head :confused:

My teacher said you must keep waffle (writing loads and not getting to any specific point) to a minumum and many students find it hard to keep within the amount of words you are needed to write. If you can, use bullet points i guess! Examiners tend to like something very easy to mark so try and incorporate annotated diagrams with small captions explaining key parts of the experiment.

I hope this helps, but i can't give in depth detail because i don't want to infringe upon cheating rules etc.
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FinalFan3
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#14
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Looks like everyone else got theirs a bit earlier than mine - got it today!!
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investor
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#15
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#15
damn when is this due in thankls everyone for your replies so far they have been very helpful
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flegghighsmells
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#16
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#16
http://www.thestudentroom.co.uk/showthread.php?t=222002
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tommygun
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#17
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#17
i am really confused now, i dont know use ammeter or voltmeter to dectect IR
can someone help plz
thkz
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flegghighsmells
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#18
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Either; it's your choice. =o)
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teachercol
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#19
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You have to measure the ouput from your photocell somehow.
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tommygun
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#20
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#20
can i ask about the length of ruler? how long i need to take for my experiment?
i am choose voltmeter bt somehow i can not measure length between IR source and photo detector
thkz u very much for ur helping
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