Is Voltage The Same In Parallel: 3 Important Explanations


This article highlights on Why Is Voltage The Same In Parallel. In any parallel combined circuit, the voltage gain in the battery is the same as each of the branches. Therefore, we get the same voltage drop across each of these resistors. Let us try another approach to understand this phenomenon.

Suppose, we have a bucket with some holes in its lower surface. Some different sized pipes are fitted through the holes. We place this container under a tap and open the tap. When water fills the container, it starts to leak through the holes.The initial velocity of water when it starts falling through the pipes, is the same for all the pipes. Similarly, by comparing this instance with voltage, we can say that the voltage is also the same when the connection is parallel.

Just the way the amount of water coming down depends upon the area of the pipes, the currents in the parallel branches depend on the resistance values. 

Read more about Can voltage be negative

What is a parallel circuit? Explain the current and equivalent resistance in parallel circuits.

We define a parallel electrical circuit as the conjunction of two or more branches that initially divides the current, then again recombines.

We can construct a circuit in series, in parallel or in combination of both. The voltage is the same everywhere in a parallel circuit as each component of the path is directly connected to both the positive and the negative battery terminals. In figure 1, we can clearly understand that the points A, C and E are identical as they have the same potential. Similarly, the points B, D and F also possess the same potential. So the potential difference across each of the following branches are the same.

Suppose we have an electrical circuit where three resistors R1 R2 and R3 are joined in parallel connection as depicted in figure 2.  The supply voltage is taken as V. Now we consider the total current as I, and the individual branch currents as I1, I2 and I3

We know, V= Vr1=Vr2=Vr3 and current through any resistor = V/ value of that resistor. 

Therefore, total current [Latex]I=I_{1}+I_{2}+I_{3}=\frac{V}{R_{1}}+\frac{V}{R_{2}}+\frac{V}{R_{3}}=V(\frac{1}{R_{1}}+\frac{1}{R_{2}}+\frac{1}{R_{3}})[/Latex]

If we assume the equivalent resistance to be R, then I=V/R

So, [Latex]\frac{V}{R}=V(\frac{1}{R_{1}}+\frac{1}{R_{2}}+\frac{1}{R_{3}})[/Latex]

Or, [Latex]R=\frac{1}{\frac{1}{R_{1}}+\frac{1}{R_{2}}+\frac{1}{R_{3}}}[/Latex]

Hence, [Latex]I=\frac{V}{\frac{1}{R_{1}}+\frac{1}{R_{2}}+\frac{1}{R_{3}}}[/Latex]

By utilizing this equation, we can further find out the branch currents.

Is Voltage The Same In Parallel- circuit example

How to calculate voltage in a parallel circuit? Explain with a numerical example.

Figure 3 illustrates a parallel electrical network comprising a few resistors. We shall learn how to calculate the voltage along with the currents in individual branches. 

In the above network, three resistors of 45 ohm, 90 ohm and 180 ohm are kept in parallel. It is given that the total current flowing through the network is 3.5 Amp. A V Volt supply voltage is provided. Now, we are expected to calculate the value of V and three branch currents.

Let us first find out the equivalent resistance of the network using the formulas we derived earlier. So, 

[Latex]R_{eq}=\frac{R_{1}R_{2}R_{3}}{R_{1}R_{2}+R_{2}R_{3}+R_{1}R_{3}}=\frac{180\times 90\times 45}{180\times 90+90\times 45+180\times 45}=25.7 \: \; ohm[/Latex]

Therefore, V=IR = 25.7 x 3.5 = 90 Volt

Now, we can easily get the individual branch currents by dividing the supply voltage with respective resistor elements.

I1= V/R1 = 90/45 = 2 amp

I2= V/R2 = 90/90 = 1 amp

I3= V/R3 = 90/180 = 0.5 amp

Is Voltage The Same In Parallel-FAQs

What are the applications of voltage in parallel?

One major advantage of the parallel circuits is that they can operate independently without disturbing the entire circuitry. So, these networks are often seen in various applications.

Some of the applications of voltage in parallel includes-

  • Home distribution system: Home wiring is always accomplished using parallel circuits. So, if one appliance fails, it doesn’t harm any other part. Had this wiring been done in series, even a simple short circuit would have caused disruption of the entire connection.
  • ‌ Car accessories: Though some of the car accessories utilizes series circuits, the headlights and some other equipment are connected in parallel circuitry.
  • Cell phone circuit: Many areas of cell phone circuit have parallel configuration. The power IC supplies power to the processor, memory, display, sensors etc. generating a large parallel circuit.

Why is voltage the same in parallel circuits but not in series?

If we observe the parallel circuits closely, we see that the positive terminal of the battery is joined to all the resistors’ positive terminal. Similarly, the negative terminal of the battery is joined to all the resistors’ negative terminal. Hence, there’s no chance of extra voltage drop which can change the voltage. 

In the series network, the supply voltage is getting divided each time it passes through the resistors. So the voltage cannot not be the same for every resistive component.

What is the effect of voltage in parallel?

Voltage results in charge carriers’ uniform flow in a circuit. 

The voltage remains the same for every branch joined in parallel. In practical life, we see that bulbs connected in parallel show equal luminosity while series connected bulbs show different luminosity (depending upon resistor value). 

How is total voltage measured in parallel connection?

The total voltage is the simple aggregate of all the individual resistor voltages taking part in parallel combination.

Just the way we mentioned before, we can find the total voltage by just summing up all the single resistor voltages. For example, we have three resistors R1, R2 and R3 joined parallel, and respective voltages are Vr1, Vr2 and Vr3. So the total voltage as defined earlier will be, Vtotal = Vr1 + Vr2 + Vr3.

Is voltage constant in parallel circuits?

The voltage drop through every resistive element in a parallel circuit is the same, but it’s not constant.

The word ‘constant’ is used in places where we intend to specify a fixed value. Voltage is never a constant quantity in a parallel circuit. Just the amount of voltage drop within parallel connected resistors is the same for a particular supply voltage. We can understand this with another simple analogy; two trees in a field can have the same height with respect to the ground level, but the height cannot be said to be constant.

Kaushikee Banerjee

I am an electronics enthusiast and currently devoted towards the field of Electronics and Communications . My interest lies in exploring the cutting edge technologies. I'm an enthusiastic learner and I tinker around with open-source electronics. LinkedIn ID- https://www.linkedin.com/in/kaushikee-banerjee-538321175

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