It is generally represented by the symbol G. Conductance is the reciprocal of resistance. The parallel connection of resistors gives the value of Conductance. Similarly, if three resistors of equal resistance R are connected in parallel combination then the equivalent resistance of the combination is R / 3. If two resistors of equal resistance R are connected in parallel combination then the equivalent resistance of the combination is R / 2. If there are two resistors in parallel then the equivalent resistance is (1/R eq) = (1/R1) + (1/R2) + (1/R3) + ……… + (1/Rn)Īn observation can be made from the above equation that the equivalent resistance of resistors connected in parallel is always smaller than the resistance of smallest resistor. The equation for equivalent resistance R eq is shown below for a parallel resistive circuit of n resistors. The inverse of this algebraic sum will give the equivalent resistance. If R eq is the equivalent resistance of the circuit then it is calculated from adding the reciprocal values of individual resistances (1/R). Therefore V / R T = V / R 1 + V / R 2 + V / R 3 If R T is the total resistance of the circuit then It has been established that the voltage across each resistor in a parallel combination is same and the total current is equal to sum of individual currents. Equivalent resistance FormulaĪny number of resistors connected in a parallel combination can be replaced by a single resistor with the resistance equal to the equivalent resistance of the parallel combination resistors. According to Kirchhoff’s Current Law, “the sum of currents entering a node is equal to the sum of currents leaving the node.”
If I1 is the current flowing through the resistor R1, I2 is the current flowing through the resistor R2 and I3 is the current flowing through the resistor R3 then the currents I, I1, I2 and I3 can be related with the help of Kirchhoff’s Current Law. Hence in case of parallel resistive circuits, the current is not same in all the resistors. The current flowing through each resistor is dependent on its resistance. If I is the current leaving the node A then it has three paths to reach the node B. V R3 is the potential across the resistor R3.īut the current flowing through these three resistors is different. V R2 is the potential across the resistor R2. V R1 is the potential across the resistor R1. Since the resistors R1, R2 and R3 are connected in parallel combination the potential difference across each resistor is same as the supply. Here the supply potential is V AB between the points A and B. In the following circuit, the resistors R1, R2 and R3 are connected in parallel combination. The potential difference across the resistor R1 is same as that across the resistor R2 which is equal to the supply potential V AB. For example, the circuit shown below is a parallel connection of resistors. This can be identified by the presence of more than one path for the current to flow. Resistors in parallel connection are connected to the same nodes. If two or more resistors are connected in parallel, then the potential difference across each resistor is same. Hence parallel resistor circuits are current dividers.
Parallel resistance formula series#
In a network of parallel resistors, current can take more than one path unlike in series resistor network as there are multiple paths for the current to flow. R=V/I: Resistance is the quotient of voltage (V) ÷ current(I).Two resistors are said to be connected in parallel if both the terminals of a resistor are connected to each respective terminal of other resistor.I=V/R: Current is the quotient of voltage (V) ÷ resistance (R).V=IR: Voltage (V) is the product of current (I) * resistance (R).If you know any two of these variables, you can easily calculate the third. This is Ohm's law, defined by George Ohm in the early 1800s. How you wire multiple resistors together makes much difference on the overall performance of a resistive network.Ceramic, on the other hand, is so resistive that it makes an excellent insulator. You can see that copper, which is commonly used in electrical wiring, has a very low resistivity. The higher the number, the greater the resistance to electrical current.Ceramics have a resistivity around 10 14(Ω/cm 3).Copper, for example, has a resistivity of 0.0000017(Ω/cm 3).Different materials have different resistance properties.
Every material that conducts electrical current has resistivity, which is the resistance of a material to electrical current.
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