Solved Examples on Series Circuit Formula
Example 1: A series circuit consists of a 12V battery, a 4Ω resistor, and a 6Ω resistor. Find the total resistance, current, and voltage drop across each resistor.
Solution:
1. Total resistance in a series circuit is equal to the sum of the individual resistances:
Total resistance, RT = R1 + R2 = 4Ω + 6Ω = 10Ω
2. Using Ohm’s law, the current in the circuit is:
Current, I = V / RT = 12V / 10Ω = 1.2A
3. The voltage drop across each resistor can be calculated using Ohm’s law:
Voltage drop across 4Ω resistor, V1 = I × R1 = 1.2A × 4Ω = 4.8V
Voltage drop across 6Ω resistor, V2 = I × R2 = 1.2A × 6Ω = 7.2V
The total voltage drop across the circuit is the sum of the individual voltage drops:
VT = V1 + V2 = 4.8V + 7.2V = 12V
Example 2. A series circuit has a 120V power source, a 10Ω resistor, and a 15Ω resistor. Calculate the current flowing in the circuit and the voltage drop across each of the resistor.
Solution:
Total resistance in the series circuit:
RT = R1 + R2 = 10Ω + 15Ω = 25Ω
Using Ohm’s law, the current in the circuit is:
I = V / RT = 120V / 25Ω = 4.8A
The voltage drop across each resistor can be calculated using Ohm’s law:
Voltage drop across 10Ω resistor, V1 = I × R1 = 4.8A × 10Ω = 48V
Voltage drop across 15Ω resistor, V2 = I × R2 = 4.8A × 15Ω = 72V
The total voltage drop across the circuit is the sum of the individual voltage drops:
VT = V1 + V2 = 48V + 72V = 120V
Example 3. A series circuit has a 220V power source, a 100Ω resistor, and a light bulb with an unknown resistance. If the current in the circuit is 2A, find the resistance of the light bulb.
Solution:
Total resistance in the series circuit:
RT = V / I = 220V / 2A = 110Ω
The resistance of the light bulb can be found by subtracting the known resistor from the total resistance:
Rlight bulb = RT – R1 = 110Ω – 100Ω = 10Ω
Series Circuit Formula
A series circuit is one of the most important concepts of electrical and electronics courses. In a series circuit, all the components are sequentially arranged and connected with each other to form a single current path. The installed total resistance is the sum of all individual resistors’ resistances. Hence, the total voltage drop is also the sum of the individual voltage drops across the respective resistors. This article will cover the equations, simplifications, and uses of series circuit systems.