Electrical Resistance

What is electrical resistance, what does it depend on and what are its applications?

The online electrical resistance simulations on this page will help you to better understand this important quality of materials and to know its relationship with other electrical quantities such as electrical current and voltage.

Electrical resistance is a property of materials that opposes the flow of electric current through them. It is measured in ohms (Ω) and is symbolized by the letter “R”.

Electrical resistance depends on several factors, such as the type of material, its length, its cross-sectional area and its temperature. Materials that exhibit high resistivity, such as tungsten or nichrome (nickel-chromium alloy), are commonly used in the manufacture of resistors.

Electrical resistance is calculated using Ohm’s law, which states that the current (I) flowing through a conductor is directly proportional to the voltage (V) applied and inversely proportional to the resistance (R) of the conductor. The relationship is expressed by the formula:

I = V / R


I is the current in amperes (A)

V is the voltage in volts (V)

R is the resistance in ohms (Ω)

Resistors are used in a wide variety of electrical and electronic applications to limit current, control power and divide voltage. They are also used in circuits to protect sensitive components by limiting the amount of current flowing through them.

There are different types of resistors, such as fixed resistors and variable resistors (potentiometers and rheostats), which allow their resistance value to be adjusted. There are also special resistors, such as temperature-sensitive resistors (thermistors) and light-dependent resistors (photocells or LDRs).

It is important to note that resistors have a limited capacity to dissipate energy in the form of heat. If their capacity is exceeded, they can be damaged or even burned out. Therefore, it is essential to select a suitable resistor for the specific application and to consider the maximum power it can dissipate without overheating.

Electrical resistance of a wire

Observe the changes in the equation and the wire as you play with resistivity, length and area.


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