How to calculate how much current is used?

[Lac]

if i want to calculate how much current my circuit draws when two resistors are connected in serie at 12VDC, I have to add the value of the two resistors ,before using ohms law, rigth[/u]

 

[Styx]

yes

 

[Lac]

but..uhh.. connecting the resitors in paralell would mean that less current is drawn? :?

 

[jrz126]

more current would be drawn since the equiv. resistance is 1/r1+1/r2=1/Rt
which is less than R1+R2 when they are in series.
and less resistance means more current drawn.

 

[Styx]

no you just asked for series.

two resistors is series produces a net resistance of hte sum of those resistors

R = R1 + R2

Via Ohms law.
V = I*R

For resistors in parallel the total resistoacne is

1/R = 1/R1 + 1/R2 + ...

 

[Lac]

but..uhh.. connecting the resitors in paralell would mean that less current is drawn?

oh sorry i meant:

Connecting the resitors in paralell would mean that MORE current is drawn.

Then it would basically to better to connect components in serie, rather than parallel, as far as it is possible?

thanks.

 

[panic mode]

that depends on what are you trying to achive - define "better".
if you take everything out of your TV and connect it in series,
i don't think you would get significant improvements other than
chance to buy new one.

 

[Lac]

In terms of "better" I mean that the circuit consumes less current.

 

[Nigel Goodwin]

In terms of "better" I mean that the circuit consumes less current.

As already mentioned, it depends entirely on the circuit, you use serial or parallel connections depending on what you want to do - or just use a single resistor of the correct value.

 

[Styx]

two 2k resistors in parallel would be the same as two 500R in series.

parallel-series, series-parallel, they are just tachneques to get a value of resistance.

what voltage are you working at and what current do you want.

That will tell you the overall load impedance, from that it is just a matter of calculation