Basic Electronics on the Go - Potential Difference in Resistor Networks

From  http://www.electronicshub.org/potential-difference-in-resistor-networks/

Potential Difference Definition

Consider a task of moving a charge from A to B in a uniform electric field. Let this movement be against  the electric field. Some work will be done by an external force on this charge and this work will change the potential energy to a higher value. The amount of work done is equal to the change in potential energy. This change in potential energy will result in a difference in potential between the two points A and B. This difference in potential is called Potential Difference and it is measured in Volts (V).

Potential Difference is denoted by ∆V and is defined as the difference in potential or voltage between two points.

If V_A is the potential at A and V_B is the potential at B, then from the definition of potential difference,

∆V_BA = V_B – V_A

Current flows in an electrical circuit in the form of charge whereas potential doesn’t flow or move. Potential difference is applied between two points.

The unit of potential difference between two points is Volt. Volt is defined as the potential drop across a 1 Ohm (Ω) resistor with 1 Ampere of current flowing through it.

Hence

1 Volt = 1 Ampere×1 Ohm

V = I × R

According to Ohm’s law, the current flowing in a linear circuit is directly proportional to the potential difference across the circuit. Hence if the potential difference applied across the circuit is greater, then the current flowing in the circuit is larger.

Generally in electrical circuits the lower potential is earth or ground. This value is usually considered 0 V. Hence the potential difference is equal to the applied voltage. Earth is considered as the common point in a circuit. This reference of earth or ground as common point in electrical circuits is useful in easy understanding of the circuit. Potential difference is also called voltage.

Voltages connected in series are added to give total voltage in a circuit. This can be observed in resistors in series connection. If V1, V2 and V3 are connected in series then total voltage VT is given by

VT = V1 + V2 +V3.

In case of elements connected in parallel, the voltage across them is equal. This can be observed in resistors in parallel tutorial.

VT = V1 = V2 = V3.

Voltage Divider Circuit

Resistors in series connection are used to produce a voltage divider circuit. Voltage divider is a linear circuit whose output voltage is a fraction of input voltage.

Applications of Voltage Divider Circuits

Resistors in series will form Voltage Divider Circuits. Voltage Divider principle is the basis in the construction of Potentiometer which acts as a simple voltage regulator.

Voltage Divider Circuits are used in Sensing circuits. The most frequently used sensors in the form of Voltage Divider circuits are thermistors and Light Dependent Resistors.