# Electric Current - Splitting & Resistance Explained

• jimmy42
In summary, the conversation discusses using Kirchhoff's rules to determine the current flow and resistance in a circuit with multiple resistors. The Kirchhoff's rules, specifically KCL and KVL, state that the total current in must equal the total current out at any junction, and the total voltage drops around a loop must equal zero. By following these rules and using Ohm's law, the current flow and resistance can be calculated accurately.

#### jimmy42

I'm unsure how to know how much current splits into which wire. So, let's say one wire with 10ma splits into two. On one of the wires there are two resistors each with 10k ohm and on the other wire three resistors each with 10k ohm. Does the current just split in two? Does the amount of resistance affect this?

Thanks.

hi jimmy42!

apply Kirchhoff's rules …

the sum of the voltage drops going round the loop must be zero, so the ratio of the currents must be … ?

OK, I read that law but didn't see how to apply it here.

So, is it just as simple as the wire with two resistors will have 4mA and the other 6mA?

maybe … and maybe not

if you're not guessing, then show us your Kirchhoff's equation to prove this!

I didn't know there was such an equation? I didn't use that but just ratios.

All I know is Ohms Law. so V=iR. Do I need that here?

I know the total resistance to be 12 k Ohm. The wires rejoin and then go onto other stuff.

jimmy42 said:
All I know is Ohms Law. so V=iR.

oh i see … i assumed you'd know Kirchhoff's rules …

sorry, but you do need them here …

KCL (the current law, or junction law) says total current in = total current out at any junction;

KVL (the voltage law, or loop law) says total iR round any loop = 0 (or = the voltage of any battery in the loop, if there is one) …

in this case, if you mark the current with arrows, and go round the loop adding iR for each resistor (counting i as negative if you're going the opposite way to the arrow through any particular resistor), you should get the correct result

What if the current flows in the same way for all the resistors? So the wire splits and then rejoins.

jimmy42 said:
What if the current flows in the same way for all the resistors? So the wire splits and then rejoins.

that's not possible (unless all the reisistors are on one branch) …

the resistors on one branch have to have the current going through the "wrong way" (in the loop) …

draw it and you'll see

It seems to go the same way?

-----R1-------R2-----
1------- -------1
----R3----R4---R5----

Those 1s will loop back to each other and attach to a battery, so how can it go in opposite directions?

but you said …
jimmy42 said:
So, let's say one wire with 10ma splits into two. On one of the wires there are two resistors each with 10k ohm and on the other wire three resistors each with 10k ohm. Does the current just split in two? Does the amount of resistance affect this?

… i assumed you meant that the current joined up again after the resistors, and carried on round the circuit to the other terminal of the battery

Yes that is what happens.

The drawing did not turn out so well. What is the equation? Maybe I can work it out from that.

round the loop one way …

i1R + i1R + i1R - i2R - i2R = 0

round the loop the other way …

-i1R - i1R - i1R + i2R + i2R = 0

## 1. What is electric current?

Electric current is the flow of electric charge through a conductor, such as a wire. It is measured in units of amperes (A).

## 2. How is electric current split?

Electric current can be split by using a device called a resistor, which is designed to limit the flow of current. This is commonly used in circuits to control the amount of current that flows through different components.

## 3. What is resistance?

Resistance is a measure of how much a material or device impedes the flow of electric current. It is measured in units of ohms (Ω). Materials with high resistance, such as rubber, are considered insulators, while materials with low resistance, such as copper, are considered conductors.

## 4. How is resistance related to splitting electric current?

When a resistor is used to split electric current, it creates a voltage drop. This means that some of the electric current is converted into heat and is not able to continue flowing through the circuit. The amount of voltage drop is directly related to the amount of resistance in the circuit.

## 5. What are some examples of resistance in everyday life?

Resistance can be found in many everyday objects and devices. For example, the heating element in a toaster has high resistance, which allows it to convert electrical energy into heat. Light bulbs also have resistance, which converts electrical energy into light and heat. Even our own bodies have resistance, which is why we may feel a shock when touching a live wire.