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Current Dividing in an Electrical Circuit

  • #1
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A circuit contains a 7.5V d.c power supply and three resistors. The total resistance of the circuit is 30 ohms. Why will the largest current in the 18 ohm resistor? As far as I know is that the smallest current will be in 60 ohm resistor because it has the maximum resistance. Please explain.
Thanks.
(regards)
upload_2018-4-15_14-14-13.png
 

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  • #2
BvU
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Hi,

I don't see a contradiction in your statements: All the current that the supply delivers to the circuit will have to go through the 18 ##\Omega## resistor. And yes, the 60 ##\Omega## resistor will have a smaller amount of current than the 15 ##\Omega## resistor.
 
  • #3
Hi,

I don't see a contradiction in your statements: All the current that the supply delivers to the circuit will have to go through the 18 ##\Omega## resistor. And yes, the 60 ##\Omega## resistor will have a smaller amount of current than the 15 ##\Omega## resistor.
Why won't the largest amount of current pass through 15 ohm resistor? Because lower the resistance, higher will be the current..
 
  • #4
BvU
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Current flows from high potential (voltage) -- the + of the power supply -- to low potential -- the ##-## of the power supply. On its path it has to go through resistor 18 ##\Omega## and after that it can and will branch over the other two. From the power supply + to the other end of the 18 ##\Omega## resistor there is a potential drop.

The left sides of the 60 ##\Omega## and the 15 ##\Omega## resistors are connected by a wire. So are the right sides.
In other words: the potential difference over the 60 ##\Omega## and the 15 ##\Omega## resistors is the same.
 
  • #5
Current flows from high potential (voltage) -- the + of the power supply -- to low potential -- the ##-## of the power supply. On its path it has to go through resistor 18 ##\Omega## and after that it can and will branch over the other two. From the power supply + to the other end of the 18 ##\Omega## resistor there is a potential drop.

The left sides of the 60 ##\Omega## and the 15 ##\Omega## resistors are connected by a wire. So are the right sides.
In other words: the potential difference over the 60 ##\Omega## and the 15 ##\Omega## resistors is the same.
Can we say that current divides as it flows into the resistors connected in parallel?
 
  • #6
BvU
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Yes. I used the word branching. All the current that comes into a connection point has to go out again (or else it would build up a huge potential in no time)
 

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