Is Voltage Constant In Series: 3 Important Explanations


The voltage across each resistor in a series circuit is different depending on the resistance value. So, voltage is not constant in series. Only equal-valued resistors can yield the same voltage drop.

We use the word ‘constant’ to specify a fixed value of a quantity that remains unchanged. The voltage can never be a constant parameter in any electrical circuit. Each resistor has a different voltage drop through them in a series combination. Hence, voltage in series circuits is neither same nor constant. 

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

When we connect some resistors or impedance parameters in line one after another, it is called a series circuit. A series combination has the equal current everywhere in the circuit.

Equivalent resistance in a series pattern is the sum of all individual impedance. The voltage drops through all the resistors sum up to the total voltage. The voltage drop through each component in the circuit is different. These voltage drops are calculated by multiplying the total current with the resistor value.

Read more about….series circuit function

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

Is Voltage Constant In Series - circuit

The above network depicts a simple series circuit with three resistors of 5 ohm, 10 ohm and 20 ohm. Our goal is to find the voltage drops through them. We’ll first find out the equivalent resistance.

The equivalent resistance R= R1+R2+R3= 5+20+10= 35 ohm

So, the total current= the total voltage / the equivalent resistance = 10/35= 0.29 amp

The voltage through 5 ohm resistor= 5*0.29= 1.45 Volt

The voltage through 10 ohm resistor= 10*0.29= 2.9 Volt

The voltage through 20 ohm resistor= 20*0.29= 5.8 Volt

Is Voltage Constant In Series-FAQs

How does the voltage affect current in series circuits?

Each resistor in the series circuit receives the same current in series connection. We calculate the voltage drop across them using the known resistor values. 

A series circuit is the joint of multiple impedance elements. So, if the circuit breaks at any time, the entire circuit faults and no current flows. A very common example of this is series connection of bulbs with different luminosity. If we keep on adding more bulbs, the brightness eventually goes down.

Calculate the total voltage V in the series circuit shown below.

The network depicted above shows four resistors joined in series. A battery is present in the circuit with an unknown voltage V. The current flow is 0.25 amp. We have to find out the value of V.

The voltage drop through 6 ohm resistor= 6*0.25= 1.5 Volt

The voltage drop through 8 ohm resistor= 8*0.25= 2 Volt

The voltage drop through 10 ohm resistor= 10*0.25= 2.5 Volt

The voltage drop through 12 ohm resistor= 12*0.25= 3 Volt

Therefore, total voltage of the battery = V=1.5+2+2.5+3 = 9 Volt

What are the applications of voltage in series?

Series and parallel circuits are considered as the building blocks of circuit design. They are commonly used for many current limiting applications such as voltage dividing , transistor biasing, etc.

The voltage in series circuit has varied applications. Some common applications of the voltage in series are-

  1. Voltage divider circuits
  2. TV remote batteries
  3. Fire alarm
  4. Analog filters
  5. Resonant circuits
  6. Power-line filters
  7. LED light bulb strings
  8. Internal components of automotive vehicles

How can we find individual voltages in a series circuit?

Individual voltages of the resistors in a series circuit is obtained from the total current multiplied with the resistor value. 

Suppose, there are two resistors R1 and R2 connected in series with the battery V. Therefore, the equivalent resistance Req is R1+R2. So, the voltage across any resistor = value of the resistor x total current

The voltage across R1 = V1 = V.R1 / R1+R2 Volt

The voltage across R2 = V2 = V.R2 / R1+R2 Volt

Is voltage the same in series?

The voltage is neither the same nor constant in the series circuit. Voltage drop through each resistor is different in all cases except one where all the resistors in a series network have the same value.

When the resistors in the circuit are of equal value, then only voltage drops will be the same for all the resistors. Suppose, in a three resistor containing circuit, all the resistors are of R ohm. The equivalent resistance value = R+R+R = 3R. The voltage across any resistor = V*R/3R= V/3 volt.

Explain the voltage in series with a practical example.

One very interesting example of a series circuit in practical life is the classic christmas tree lighting. In this lighting, many tiny bulbs are connected in series.

We use these bulbs over the years. We can see that a particular portion of the lights aren’t working. This is due to the series connection. The lights are the combination of many such series connected strings. So, even if one bulb in a network is damaged, the entire part stops working.

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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