Help with Physics: Calculating Resistor Values

[TonyThaGreat]

Hey guy! I am new here and I am seeking some help!
so i just started a Electric Engineering course at grimsby collage and, i thought i had some science knowlage ohms and that. you know? until they gave me this.

Calculating Resistor Values.
Two Resistors are connected in series with values of 220ohm & 390ohm

also

Two Resistors are connected in series with values of 1k2ohm & 2k2ohm

im not askin u to tell me the answer. just how grasp and work out the equasion.

i kinda just jumped in at the deep end without any know-how. one year a plumber, next an engineer.

 

[kbaumen]

If you expect to really receive some help, then show your work. If you don't know how to calculate the total resistance then take a look http://http://en.wikipedia.org/wiki/Resistor" , though your textbook (if you have one) should have all the information since this is a basic question.

 

[Feldoh]

Two resistors in series have the same current through them.

So using ohms law (V = iR) V_{total} = iR_1 + iR_2 = i(R_1+R_2)

So as you can see an equivalent resistor would just the from the addition of the two resistors.

 

[MacLaddy]

Dumb question, but is Ohm's law considered a formulation in algebra, physics, etc?
Good info on this article, and I have been reading through this forum trying to absorb some info for my own school start, but I am 15-years out of high school and I don't remember alot/any of this.

 

[berkeman]

Dumb question, but is Ohm's law considered a formulation in algebra, physics, etc?
Good info on this article, and I have been reading through this forum trying to absorb some info for my own school start, but I am 15-years out of high school and I don't remember alot/any of this.

Welcome to the PF. Not really a dumb question, but I'm afraid I don't quite understand what you are asking. Ohm's law is just an algebraic relationship between current, voltage and resistance (or more generally impedance, when you get to complex number representations). There are reasons in physics behind the algebra, however. Hope that helps some...

 

[TonyThaGreat]

ok, thanks guys i still don't fully undersatand but i kinda get the equasion. please correct me if I am wrong.
so (V = iR) so V is voltage? I - currrent, and R is resistance.
(V=iR) Vtotal = iR1 + iR2 = i(R1 + R2)
so ir1,2 are the phases the currents split off into ect.
just thinking out loud.. V x I = R. (multipling 2 to find the 3rd also works?)
also I've been reading up on this, starting to make sense.
but i still don't know what ohms law is... anyone have an link to some info
would be great!

cheers
Tony :)

 

[berkeman]

ok, thanks guys i still don't fully undersatand but i kinda get the equasion. please correct me if I am wrong.
so (V = iR) so V is voltage? I - currrent, and R is resistance.
(V=iR) Vtotal = iR1 + iR2 = i(R1 + R2)
so ir1,2 are the phases the currents split off into ect.
just thinking out loud.. V x I = R. (multipling 2 to find the 3rd also works?)
also I've been reading up on this, starting to make sense.
but i still don't know what ohms law is... anyone have an link to some info
would be great!

cheers
Tony :)

Here's an intro link:

http://en.wikipedia.org/wiki/Ohms_law

You should also read up on Series and Parallel connections of resistors, to better understand how the currents divide, and how the voltages add up.