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#### subdub

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I am studying my 2330...the maths is bogging me down a little but i think i am getting it...when all of a sudden bang...self doubt.So i wondered if any of the sparkys on here or trainees may be able to help.

It is a question at the beggining of the practical about the 2 way lighting circuit......

The circuit is 24v with two 40 w bulbs...the questions are

Note the power rating of all loads on the circuit...well all i can think of is

p=v x i

or is this to do with the testing of the circuit that i have not done yet.

It then goes on calculate the resistance of the circuit...so are the 40 watt lamps resistors...i suppose they are but to convert watts to amps

I=watts divided by voltage
So 80w/24v is 3.33amps

ohms law then makes

the resistance 7.05 ohms.

Does this sound right!!Any help advice greatly and humbly recieved. #### Valandil

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Note the power rating of all loads on the circuit...well all i can think of is

p=v x i

or is this to do with the testing of the circuit that i have not done yet.

It then goes on calculate the resistance of the circuit...so are the 40 watt lamps resistors...i suppose they are but to convert watts to amps

I=watts divided by voltage
So 80w/24v is 3.33amps

ohms law then makes

the resistance 7.05 ohms.

Does this sound right!!Any help advice greatly and humbly recieved. Power is measured in watts, and surely the only two loads on the circuit are the 2 40w bulbs, so isnt that the answer?

As for the resistance

V=IR
so R=V/I

You dont know I, but P=IV so I=P/V

so R=V/P/V

so R=V(squared)/P

I THINK thats right... i do A level physics and as far i can remember and tell, this makes sense to me...

#### Eggster71

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Thank fuck I'm done with college!!!! :lol::lol::lol:

#### subdub

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Discussion Starter · ·
quickly then....

P = V x I
80 = 24 x I

I = 3.333333333.

V = I x R
24 = 3.333333. x R

R = 7.2 Ohms.
so i was along the right lines then......just didnt put enough 3 in my 3,.33333 recurring.Ta 1 - 6 of 6 Posts