IMPACT OF “RESISTOR” IN ELECTRIC CIRCUIT

In Electric circuits, the current and voltage are two key factors to define the response of the circuits. The current is defined as the rate of change of charge carriers per second (dQ/dt), that is, the number of charged particles that moves from one point to another point in a closed loop. In the same manner, the voltage is defined as a potential difference between the two points. In other words, the term voltage is defined as the force required to move the electron from one point to another point.

Voltage and Current

             Basically, in the electric circuit, the free electrons are present along the conductor path, and there is always a small movement between the electrons due to atmospheric temperature, it creates a milliamp current. If the supply voltage is connected to the circuit, the electrons start to move from – ve terminal to +Ve terminal owing to force created by voltage.                      

               Consider  the simple electric circuit, where the battery is connected across a bulb and switch. When the switch is closed, the electrons start to move in the conductor path, and the current flow gets started so the light starts to glow.  If the switch is opened, immediately the movement of the electrons stops and it will come back to standstill position. From this above scenario, the significance of voltage and current in electric circuits is clarified.

  When the voltage level increased in the circuit; the current value also increased accordingly. So, the relationship between the current and voltage is expressed as

                                             Current ∝ voltage

230 V/1 A and 1 V /230 A which one is injurious

                  Consider one person having two wires in his hand, and one wire contains 230 V, 1 A, and another wire contains 230 A, 1 V. Among these, two wires, 230 V, 1 A only create injury to that person because the 1V circuit does not have the energy to move the electrons from one point to another point, so this wire is not likely to injure the human body.

Resistor

In electric circuits other than the current and voltage, one more factor is significant to describe the circuit response that is a resistor. Generally, electric circuits consist of a transistor, capacitor, IC, resistor, and some other electronics components. In any electric circuit, the resistor component acts as a primary key factor in defining the operation of the circuit.  To understand the essential operation of an electric circuit, the user should know basic knowledge about the resistor function, the performance of the resistor connected in series and parallel.

Need for a resistor in the electric circuit

Assume the LED is connected without resistance. In this condition if the voltage level increases higher is the voltage rating of the LED, it will burn.  We can reduce the power supply, if the LED is connected to any common power supply then the current flow is limited. For this purpose, the resistor is used in electric circuits.

Generally, the resistor is defined as ‘it opposes the flow of charge carriers. In electric circuits, the power supply connected, electrons start to move from the – ve terminal of the batter. In these circuits, the resistor connected in series it opposes the flow of charge carriers. Due to this, the speed of the charge carriers is reduced, and at the same time, the current value will be reduced because the rate of change of charge particle with respect to time makes the conduction. If the rate of movement of the charged particle is reduced by the resistor, the current flow also gets reduced. The relationship between the current, voltage, and resistance is expressed as

Current ∝ Voltage / Current

Resistors in Series Connection

 In electric circuits, more than one resistor connected in series, the current value is the same, and the voltage across the resistor is varied. The concept behind this technique is described in the below statements.  

In the above figure, the current value measured in position ‘A’ is equal to the position ‘B’ and ‘C’ because the current depends on the rate of charge particle movements with respect to time, and it is calculated between the two points in a closed path. So, the current value between any two points in the series circuit is the same.        

In a series resistance path circuit, the voltage level is different across each resistor because the resistor opposes the flow of current. The voltage (force) required to push these electrons across the resistor depends upon the resistor value. The sum of the voltage across each resistor is equal to the battery voltage. It is simply expressed as in a closed network, the sum of potential rise is equal to the sum of the potential drop.

             In a series resistor network, the resistor value increases and the current value decreases. The flow of current is increased by

• Increase the voltage level
• Decrease the resistor level
• Connect the resistors in parallel.

Resistors in Parallel Connection

The resistors are connected in parallel, the flow of electrons is increased, due to this, the flow of current is increased and the resistor value is decreased simultaneously.

Resistance in parallel: Water analogy

                     From the water analogy, the level of the water tank considers a voltage level (let it should always be constant), and three pipes are connected in parallel. In this situation, the water force in all three pipes is constant. But the water outlet amount depends upon the diameter of the pipe.  Compare this water analogy with a parallel resistance circuit, the voltage level is constant to all the parallel resistance, but the flow of current depends upon the value of the resistor. In a parallel circuit, the total current (I) is equal to the sum of current going in the parallel path (I1 +I2+I3).

                             From the above discussions, It will conclude that the resistors are used to limit the flow of current and if the resistors connected in series in the network, the resistance value is increased and the total current flowing in the circuit is the same, and the potential difference across each resistor is different. In another way, the resistors are connected in parallel, the resistance value is decreased, and the potential difference is constant across the parallel circuit, and the current value is different in each parallel circuit.