Need a little assistance from those that know Ohm's law and electricity...

Ok...I got this problem to solve for class.....

I'm at a loss...I can get Total Ohm's but without either Total Amps or Total Voltage I don't think it's possible to work out the others.....am I wrong?

I know theres a typo...R4 is supposed to be R3.....regardless it is 6 Ohm's of resistance...


Woohoo 600 posts!!!! lol

So you need to calculate Rtotal in a parallel electricity? If so, then
1/rtot = 1/r1 + 1/r2 + 1/r3
1/rtot = 1/3 + 1/4 + 1/6 = 3/4
1/rtot = 3/4
rtot = 1/(3/4) = 4/3 Ohm

This SHOULD be the correct answer, but I never was any good with electricity so I'm not sure.

As I said I can get total Ohm's...which is 1....but I need amps for each leg and total voltage....

Quote:

---

Originally Posted by Pieman

So you need to calculate Rtotal in a parallel electricity? If so, then
1/rtot = 1/r1 + 1/r2 + 1/r3
1/rtot = 1/3 + 1/4 + 1/6 = 3/4
1/rtot = 3/4
rtot = 1/(3/4) = 4/3 Ohm

This SHOULD be the correct answer, but I never was any good with electricity so I'm not sure.

---

Numpty, R1 and R2 are 2 and 3.

1/2+1/3+1/6 = 1ohm

P=V*I
144=V*I
V=I*R
V=I*1=I
P=2V
144=2V
V=144/2=72

Simple :)

Quote:

---

Originally Posted by GiantRobert

Numpty, R1 and R2 are 2 and 3.

1/2+1/3+1/6 = 1ohm

P=V*I
144=V*I
V=I*R
V=I*1=I
P=2V
144=2V
V=144/2=72

Simple :)

---

Whoa....where di you get the volts?

I am lost as to how you turned 144 W to 2 V....

Quote:

---

Originally Posted by GiantRobert

Numpty, R1 and R2 are 2 and 3.

1/2+1/3+1/6 = 1ohm

P=V*I
144=V*I
V=I*R
V=I*1=I
P=2V
144=2V
V=144/2=72

Simple :)

---

D'oh, how the hell did I manage to screw that up? :ehh:

woops its V^2 not 2V, sorry.


P=V*I (power equation)
144=V*I (put in total power, see what we need to find)
V=I*R (ohms law)
V=I*1=I (we know what the resistance is so we can put it in)
P=V^2 (since V and I are equal we can replace I with V in the power equation simplifying it to this)
144=V^2 (put total power back in)
V=root(144)=12 (opposite of power of 2 is root...)
I=12 (since V and I are equal we know what I is as well)

It looks harder than it is. The easiest way would be to use one of the other power equations P=(I^2)*2 or P=(V^2)/R but I prefer to stick with P=V*I and substitute the rest in later.

http://en.wikipedia.org/wiki/Electric_power if you still need help.