Why do resistors in series recieve the same current

[scilearner]

Helllo guys,

 

I was wandering why was this the case. If there were 3 resistors (Let's say 100ohms,200ohms,300ohms) in this seriec how can they recieve the same current if resistance is inversly proportional to current. Shouldn't the 300 ohms one recieve the least current. I thought resistors decrease the current what do they really do. Any help would be appreciated. Thanks!! :-)

[ydoaPs]

Why would the 300 ohms receive the least current? Where are the electrons going? You have a certain number of electrons moving through the wire and since they are in series, there aren't any branches for the current to take an alternate route. What comes in must come out.

[scilearner]

Why would the 300 ohms receive the least current? Where are the electrons going? You have a certain number of electrons moving through the wire and since they are in series, there aren't any branches for the current to take an alternate route. What comes in must come out.

 

Thanks for the help:-). I thought resistors decrease the current as the current goes through it. What does the resistor do. I'm talking about this formula where

 

I= V/R where R and I are inversely proportional.

[ecoli]

Thanks for the help:-). I thought resistors decrease the current as the current goes through it. What does the resistor do. I'm talking about this formula where

 

I= V/R where R and I are inversely proportional.

 

no... the current will stay the same. But, if you placed a larger resistor in there, how would that affect the voltage?

[scilearner]

no... the current will stay the same. But, if you placed a larger resistor in there, how would that affect the voltage?

 

Then the volatage required would be high. V=IR. If resistance is the force that opposes the current why does it affect the volatge not the current. Thanks for the help by the way:-)

[5614]

Then the volatage required would be high. V=IR.

Not quite, because your battery is supplying some voltage, V, and it cannot just "be higher". If you have a power supply giving out 9V and you have a 9ohm resistor then I=1A, but if you change it for a 18ohm resistor then I=0.5A, the voltage won't change, the battery gives out a constant voltage (in simple cases it does anyway!).

 

Usually the power supply won't change voltage when you change the circuit, so putting in more resistance will mean that the current is lower.

 

If resistance is the force that opposes the current why does it affect the volatge not the current.

Resistance does oppose the current. But you can also say that, in your series circuit, larger resistances will have a larger voltage drop across them.

[Klaynos]

On a related note, you get 2 types of power supply.

 

Constant voltage.

and

Constant Current.

 

As the names suggest one supplies a fixed voltage (batteries are a good example of this) and the other a fixed current, if you change the resistance in the circuit the power supply will try and match it's voltage (for constant voltage) to it's original value.

 

This is limited by the power output of the power supply though.

[YT2095]

each resistor will have a different Voltage dropped across it, that much is true.

[thedarkshade]

each resistor will have a different Voltage dropped across it, that much is true.

Beautiful said! Because the find the total resistance when resistors in the OP's case, you would do that by:

 

[math]R=R_1 + R_2 + R_2[/math] which in a complicated way would look

 

[math]IR= IR_1 + IR_2 + IR_3[/math] and since IR=U then:

 

[math]U= U_1 + U_2 + U_2[/math] and this is what YT said:-).