What is a Current Divider?
A current divider is an electrical circuit configuration used to split or divide an input current into multiple branches or paths. It consists of resistive elements connected in parallel, forming a parallel circuit. In a parallel circuit, each branch operates independently of the others, and the total voltage across each branch is the same.
The purpose of a current divider is to distribute the total current flowing through the circuit among the different branches according to their respective resistances. This is achieved by the principle that the current flowing through each branch of a current divider is inversely proportional to the resistance of that branch.
In other words, branches with higher resistance will have lower current flowing through them, and branches with lower resistance will have higher current flowing through them. This behavior is described by Ohm's Law, which states that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them.
To understand how a current divider circuit works, consider a simple example where a battery is connected to a pair of resistors in parallel. The total current from the battery is divided between the two resistors. The resistor with a higher resistance will have a smaller portion of the total current flowing through it, while the resistor with a lower resistance will have a larger portion of the total current.
This principle is useful in various applications, such as in measuring instruments where it's necessary to measure a small portion of a large current, or in electronic circuits where it's required to distribute current to different components.
Working Principle of Current Divider
The basic principle behind a current divider can be understood using Ohm's Law, which states that the current flowing through a resistor is directly proportional to the voltage across it and inversely proportional to its resistance. In a current divider, the total current (I) entering the circuit is divided between the branches based on their resistances.
The Current Divider Formula
The current through each branch (I1, I2, I3, etc.) can be calculated using the following formula:
I1 = (R2 || R3 || ...) / (R1 R2 R3 ... ) * I
Where:
- I1, I2, I3, etc. are the currents in each branch.
- R1, R2, R3, etc. are the resistances of each branch.
- (R2 || R3 || ...) denotes the combined resistance of the parallel branches.
- I is the total input current.
Current Divider Formula Example
Let's consider a practical example to demonstrate the current divider formula. Suppose we have a circuit with an input current of 2 amperes (I = 2A) and three parallel resistors connected in the circuit: R1 = 4 ohms, R2 = 6 ohms, and R3 = 8 ohms.
To calculate the current flowing through each branch (I1, I2, and I3), we can use the current divider formula:
I1 = (R2 || R3) / (R1 R2 R3) * I
I2 = (R1 || R3) / (R1 R2 R3) * I
I3 = (R1 || R2) / (R1 R2 R3) * I
Let's substitute the given values into the formula:
I1 = (6 || 8) / (4 6 8) * 2
I2 = (4 || 8) / (4 6 8) * 2
I3 = (4 || 6) / (4 6 8) * 2
To simplify the calculations, we need to calculate the equivalent resistances of the parallel combinations:
R2 || R3 = (R2 * R3) / (R2 R3)
R1 || R3 = (R1 * R3) / (R1 R3)
R1 || R2 = (R1 * R2) / (R1 R2)
Substituting the resistances:
R2 || R3 = (6 * 8) / (6 8) = 48 / 14 ≈ 3.43 ohms
R1 || R3 = (4 * 8) / (4 8) = 32 / 12 ≈ 2.67 ohms
R1 || R2 = (4 * 6) / (4 6) = 24 / 10 = 2.4 ohms
Now, we can substitute these values back into the current divider formula:
I1 = 3.43 / (4 6 8) * 2
I2 = 2.67 / (4 6 8) * 2
I3 = 2.4 / (4 6 8) * 2
Calculating the currents:
I1 ≈ 0.2457 A (or 245.7 mA)
I2 ≈ 0.1917 A (or 191.7 mA)
I3 ≈ 0.1722 A (or 172.2 mA)
So, in this example, the current flowing through branch 1 (I1) is approximately 0.2457 amperes, the current through branch 2 (I2) is approximately 0.1917 amperes, and the current through branch 3 (I3) is approximately 0.1722 amperes.
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Applications of Current Dividers
- Biasing in transistor circuits: Transistors require specific current levels to operate within their desired operating range. Current dividers can be used to provide the necessary bias currents to the base or gate terminals of transistors, ensuring proper functionality.
- Current sharing in power supplies: In power supply circuits with multiple parallel output channels, current dividers are used to distribute the total output current evenly among the parallel channels. This helps balance the load and prevents overloading of any single channel.
- Sensing and measurement: Current dividers are used in current sensing applications, where a fraction of the main current is diverted to a sensing resistor. This allows for accurate measurement of the current without affecting the main circuit operation.
- Current limiting and protection: Current dividers can be employed in circuits to limit or regulate the current flowing through specific components. By setting the appropriate resistance values, the current can be controlled to prevent component damage or ensure safe operation.
- Voltage-to-current conversion: In some cases, a voltage source needs to be converted into a proportional current. Current dividers can be used with appropriate resistive elements to achieve this conversion, providing a current output that is directly proportional to the input voltage.
- Signal distribution: In communication systems or signal processing circuits, current dividers can be used to split an input signal into multiple branches, allowing the signal to be distributed to different components or subsystems.
- Wheatstone bridge circuits: Wheatstone bridges are commonly used for measuring unknown resistances or for sensing changes in resistance. Current dividers are an integral part of these bridge circuits and help balance the bridge and provide accurate measurements.
These are just a few examples of how current dividers are utilized in various applications. The flexibility and controllability of current division make it a valuable tool in electrical and electronic circuit design.
Current Divider vs. Voltage Divider
Voltage and current division are two common methods of dividing power in electrical circuits, used to distribute current or voltage to different branches of a circuit. While they serve different purposes, they are both based on Ohm's Law and can be used to calculate the distribution of current or voltage in a circuit.
Voltage and Current Divider Formula
A current divider is used to distribute current among multiple parallel resistors. The current divider formula describes how the current across parallel resistors is distributed according to their respective resistance values. The current divider formula is very useful when it is necessary to distribute current to multiple parallel loads or sensors.
The formula for the current divider is shown above, that is:
I1 = (R2 || R3 || ...) / (R1 R2 R3 ...) * I
On the other hand, a voltage divider is used to distribute voltage among multiple series resistors. The voltage divider formula describes how the voltage across series resistors is distributed according to their respective resistance values. The voltage divider formula is very useful when it is necessary to reduce voltage to a specific value or distribute voltage among multiple devices.
The formula for the voltage divider is:
V1 = (R1 / (R1 R2)) * V
Where:
- V1 is the voltage across the specific resistor.
- R1 and R2 are the resistances of the resistors.
- V is the total input voltage.
What is the difference between Current Divider and Voltage Divider
Current division is the process of distributing the total current to different resistive branches. In a parallel circuit, the current is divided according to the resistance values of each branch. Current division focuses on how current is distributed among resistors.
Voltage division, on the other hand, is the process of distributing the total voltage to different resistive branches. In a series circuit, the voltage is divided according to the resistance values of each branch. Voltage division focuses on how voltage is distributed among resistors.
ALSO READ: DC Voltage: What is It & DC VS AC Symbols
Here is a useful video:
current dividers explained
