What is an electrical resistor?

Answer 1

When an electric current moves through a conductor, there is always some electrical resistance to the current. This is because of the attraction of the electrons to the positive nuclei of the atoms in the conductor. This attraction is greater in some conductors than in others, giving them a greater electrical resistance.

As the electrons are pushed through a conductor they lose some of their energy as heat. This waste heat can be a nuisance; for example, computers get hot when used. However the waste heat is sometimes useful. For example, because nichrome wire has a fairly high resistance, it is used to make the heating elements in many electrical appliances used around the home. It is usually coiled to take up less space. The filament of a light bulb is made of very thin tungsten wire. When a current is passed through it, the wire becomes so hot that it gives off a brilliant white light.

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Thanks George
Electrical resistance exacts a voltage drop as the price for allowing electrical current to flow through the resistance. The use of the term resistance implies that the current flow will be in phase with the voltage across the resistor and that the current flow will be proportional to the voltage drop. These conditions are Ohm's Law. There are devices which do not meet these conditions. They can be useful, but they should be considered as another component class such as thermistors etc. Mathematically V = I x R, where V is the instantaneous voltage across the resistance, I is the instantaneous current through the resistance, and R is a constant specific for the resistance. If V is in Volts and I is in Amperes, then R will be in Ohms. Practical resistors vary modestly with temperature, but change very little with voltage or current, except as these change the temperature. A resistor should be the same for flow in either direction and for DC and AC of modest frequency. At high frequencies resistors can display inductance and/or capacitance.

Resistors can be purchased with various resistance tolerances, with various temperature sensitivities, and with various power ratings. Running at full power rating may shorten life and may produce temperatures which affect adjacent components. Derating to 1/2 or even 1/3 power may be wise.
It is a measurement of how hard electricity flows thru specific area. In SI is measured in ohm.
Resistance is the opposition to the flow of electric current, and is measured in ohms. Resistance is directly proportional to the length of a conductor and inversely proportional to its cross-sectional area, and directly proportional to the resistivity of the material from which the conductor is manufactured. As resistivity is affected by temperature, resistance is indirectly affected by temperature.

An example of an electrical resistance is a bar-type radiant heater. The resistance in the windings (these are usually of small diameter wire) causes the electrons to flow slower, causing heat which manifests itself as the hot glow you see and the warmth you feel.

Answer 2

Resistance is the opposition offered by a material to the passage of an electric current. Resistance is directly-proportional to the length of that material and inversely-proportional to its cross-sectional area. Its constant of proportionality is called 'resistivity', which depends on the type of material, and its temperature.

Answer 3

Electrical resistivity is an intrinsic property that quantifies how strongly a given material opposes the flow of electric current.

Electrical resistance is defined as R = V/I.

That is, resistance = voltage/current flowing through it

Answer 4

An electrical resistor is a device that resists the flow of electric current. It is measured in Ohms and the resistance in a circuit can be related to voltage and current flow by the equation v=ir, where v is the voltage, measured in volts, i is the current, measured in amperes, and r is the resistance.

Answer 5

It is resistance to the flow of electricity in the path or passage of flow when contacts are in motion. refer ZARA effect.