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BRMark
11-03-2009, 08:53 PM
an electrical engineering degree!?

I need help with this question for my assignment.

Lighting circuit connected to a 230v supply has 8no 100w lamps connected in parallel - how many ohms resistance does each lamp have?

If it helps I've worked out the amps to be 3.48





Sodding collage work :mad:
BRMark
11-03-2009, 08:54 PM
On a side note....400th post! wooohoooo!
andrewbrm
11-03-2009, 09:31 PM
Resistance = v/a (/ is a divide symbol!). We know the voltage but we don't know the amps.

A = W/V so 100w / 230v = 0.4347826A

R = V/A so 230V / 0.4347826A = 529 OHMs. The resistance of one bulb is 529 OHMs

That's how I'd do it with my limited knowledge.
boogie
11-03-2009, 10:45 PM
I throw all my stuff out with the formulas about a month ago because I would not need it anymore. From memory andrew is right ( i am getting old) sodding ohms law
garythesnail
11-03-2009, 11:03 PM
Different method, but same answer as Andrew and Boogie.

V=IR, P=VI and for resistors in parallel 1/R = 1/r1 + 1/r2 + 1/r3 etc. I think Andrew just applied logic which I lost years ago after scraping through A-level physics
andrewbrm
11-04-2009, 01:08 PM
Lamps are a resistive load, so you don't need AC theory. AC theory will blow your mind.
garythesnail
11-04-2009, 04:46 PM
Who mentioned AC theory?

More to the point - what's AC theory? :D I haven't got a clue!

On second thoughts, if AC theory will blow your mind, best not answer.
Bornunder Dutchess
11-04-2009, 07:30 PM
Ive done some careful calculations....


And the answer is.......


CHEESE! :)
Rockey5uk2001
11-04-2009, 08:26 PM
lol ur nuts
Bornunder Dutchess
11-04-2009, 08:34 PM
or am I?
BRMark
11-04-2009, 08:39 PM
Cheese you say....


*copies into assignment*
Bornunder Dutchess
11-06-2009, 07:36 AM
*looks over Marks Shoulder at paper*


you spelt it wrong.
andrewbrm
11-06-2009, 01:08 PM
Oh dear, another thread descends into the surreal world inhabited by Bornunder Dutchess.
BRMark
11-06-2009, 01:49 PM
As my education crumbles :cry:
Adam
11-06-2009, 02:13 PM
Oh dear, another thread descends into the surreal world inhabited by Bornunder Dutchess.

I've noticed this :wacko:
Bornunder Dutchess
11-08-2009, 04:38 PM
.......Don't encourage me then!!!
andrewbrm
11-08-2009, 05:29 PM
.......Don't encourage me then!!!

Who's been encouraging you? I hope it wasn't me.
Bornunder Dutchess
11-08-2009, 08:29 PM
It was you...Bad Andrew!:chair:
andrewbrm
11-08-2009, 09:17 PM
Don't hurt me. Please!!!!!
Bornunder Dutchess
11-09-2009, 01:28 AM
:shoot:
eurorover
11-09-2009, 11:02 AM
66.88 ohms i think
andrewbrm
11-09-2009, 12:12 PM
:shoot:

Does the number of smilies keep increasing? I haven't seen that one before.

By the way, BRMark, have you had your assignment marked yet?
Adam
11-09-2009, 12:57 PM
Click on 'Go Advanced' in the quick reply box, find the little smiley face beside the font/size options, etc, scroll to the bottom and click on 'Show All Smilies' :hump: :w00t::band::group::soldiers::jacko::weakbench::su per::chop::gathering::bike:
BRMark
11-10-2009, 08:52 AM
Resistance = v/a (/ is a divide symbol!). We know the voltage but we don't know the amps.

A = W/V so 100w / 230v = 0.4347826A

R = V/A so 230V / 0.4347826A = 529 OHMs. The resistance of one bulb is 529 OHMs

That's how I'd do it with my limited knowledge.

That was correct, I've not had the assignment marked yet but we went over a similar question yesterday and I applied it to my assigment question!
Bornunder Dutchess
11-11-2009, 01:04 PM
..not cheese then??