Enter data and then click on the quantity you wish to calculate in the active formula above. Upon changes, the values will not be forced to be consistent until you click on the quantity you wish to calculate. This formula relates the resistance of a conductor with its specific resistance (the Greek letter “rho” (ρ), which looks similar to a lower-case letter “p”), its length (“l”), and its cross-sectional area (“A”).

A resistor is an electronic component used in the circuit in order to offer that particular amount of resistance. The resistance across any object is calculated using the formula. Where, v = Voltage applied across its ends.

Electrical resistance is a property of materials that allow electric current to flow. The unit of resistance is Ohms, which is represented with the Greek uppercase letter omega: Ω. Resistance opposes the flow of current. Another situation for which this formula is not exact is with alternating current (AC ), because the skin effect inhibits current flow near the center of the conductor.

For this reason, the geometrical cross-section is different from the effective cross- section in which current actually flows, so resistance is higher than expected. The current through each resistor in series is equal, but the voltage is not. For a more detailed explanation and practical examples, refer to the article resistors in series.

Sometimes the desired value is not available with standard preferred values. Using the flow analogy. Where ρ is the resistivity of the conductor in Ω. A is the Cross-sectional area in metres. There are many reasons why parallel resistor networks or series resistor networks may be used.

It is possible that the required value may not be available, and a combination of two or more may provide the required . Materials naturally have some resistance to the flow of an electric current. Some materials resist the flow of current more than others, and therefore it is known as the electrical resistivity of the substance. The term electrical resistivity may also be known as the specific electrical resistance , or volume resistivity in some . Or in equation forP = VI. Remember, when solving for total resistance , you need to know the total power of the circuit.

Then the inverse of the equivalent resistance of two or more resistors connected in parallel is the algebraic sum of the inverses of the individual resistances. If the two resistances or impedances in parallel are equal and of the same value, then the total . Ohm did that and he decided to call k resistance , and use the letter R for it. What is the voltage across this device?

This physics video tutorial explains the concept of resistivity and resistance of electrical conductors like copper. Derive the series resistance formula. For the case of three differently valued resistors labeled , prove that the equivalent resistance of all of them together is.

Calculating resistance. The combined resistance of two resistors in series is the sum of the resistance values of the two resistors in ohms.