# Why would a parallel circuit (or in blood) decrease resistance

• hongiddong
In summary, adding more arterioles in parallel decreases resistance in a circuit or in blood flow. This is because a larger total flow area means a lower speed for the fluid, leading to a decrease in fluid friction and ultimately resulting in a lower resistance.
hongiddong
Hi PhysicsForums,

Why would a parallel circuit(or in blood) decrease resistance?

Here is my thought experiment and where I got stuck:

Say from aorta to one arteriole, the resistance is super high on that flow(this big amount of flow is entering a tinier area), but add more arterioles and we have a bigger area in total and blood can flow better(but whyyyy) Why would having a greater area conceptually help with the resistance?

For the same total volume flow, more paths in parallel mean that less blood is required to flow through each, and the consequent lower flow rate in each means there is reduced fluid friction to overcome.

hongiddong
hongiddong said:
Hi PhysicsForums,

Why would a parallel circuit(or in blood) decrease resistance?

Here is my thought experiment and where I got stuck:

Say from aorta to one arteriole, the resistance is super high on that flow(this big amount of flow is entering a tinier area), but add more arterioles and we have a bigger area in total and blood can flow better(but whyyyy) Why would having a greater area conceptually help with the resistance?

Look at the continuity equation for fluid flow. See if you can figure out why a larger total flow area means a lower speed for the fluid. Then apply what NascentOxygen has stated.

Zz.

hongiddong
If you define the resistance as rate of flow divided by pressure difference then the flow will double and, thus, your resistance will halve.

hongiddong

## 1. Why is a parallel circuit more efficient than a series circuit?

A parallel circuit is more efficient because the current is divided into multiple branches, allowing it to flow through each branch with less resistance compared to a series circuit where the current has to flow through each component in sequence, resulting in a higher total resistance.

## 2. How does a parallel circuit decrease resistance?

In a parallel circuit, each branch provides an additional path for the current to flow, resulting in a decrease in overall resistance. This is because the total resistance in a parallel circuit is calculated by adding the reciprocals of each branch's resistance, which is always less than the individual resistances.

## 3. What is the effect of adding more components in a parallel circuit?

Adding more components in a parallel circuit has the effect of reducing the total resistance of the circuit. This is because each new branch provides an additional path for the current to flow, resulting in a decrease in overall resistance.

## 4. How does the resistance in a parallel circuit compare to a series circuit?

The resistance in a parallel circuit is always less than the resistance in a series circuit with the same components. In a parallel circuit, the total resistance is calculated by adding the reciprocals of each branch's resistance, while in a series circuit, the total resistance is simply the sum of all the individual resistances.

## 5. Can a parallel circuit have an infinite resistance?

No, a parallel circuit cannot have an infinite resistance. The total resistance in a parallel circuit is always less than the smallest resistance in any of the branches. Therefore, as long as there is at least one branch with a finite resistance, the total resistance of the parallel circuit will also be finite.

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