Resistance vs Resistor
Whenever there is factor hindering the desired action of anything we say there is a resistance to that action. We experience this situation in electrical circuits too. When an electric current passes through a material, it poses a resistance to the flow of the current. This is simply known as the electrical resistance and the magnitude of resistance to the flow of current differs from material to material.
What is Resistance?
In physics and electrical engineering, resistance is defined as the ratio of the potential difference across the terminals of an element to the electrical current passing through it. It is a measure of the elements opposition to the passing of electrical charge. The above definition is mathematically expressed as R = V/I, where R is the resistance, V the potential difference, and I the electric current. The inverse of the resistance is defined as the conductance of the material.
Resistance is mainly dependent on two factors; the geometry of the element and the material. Since electrical current is a continuous flow of electrons through the material the width (diameter) of the conductor affects the resistance, just like the diameter of a pipe determines the maximum flow it.
The other factor is the material, specifically the electron configuration and the bonding of the molecules or ions present in the material. When a potential difference is applied to the ends of an element it acts like a pressure difference applied to the ends of a pipe. The electrons are excited to a higher energy level range called the conduction band and the electrons are loosely bound to the nuclei of the atoms by electromagnetic forces allowing greater mobility to the electrons. If the materials are metallic, the outermost electrons are already in the conduction band at room temperature, hence becomes good conductors having low resistance. Materials with covalent bonding present in the structure, such as wood, glass and plastics have electrons tightly bound to the nuclei and the energy required to raise the electrons to the conduction band is much greater than that of metals and shows a high resistance. The property of resistance offered by a material is quantified as the resistivity of the material. Since the energy of electrons is dependent on the temperature, the resistivity also depends on the temperature.
This property is also used as a means of categorizing materials. The materials with low resistivity are known as conductors, and materials with medium resistivity are known as semi-conductors and materials with high resistivity as the insulators.
What is Resistor?
An important property offered by the resistance of a fixed element is that, at a constant potential difference, a constant current flow through the element. Therefore, the current through a circuit can be controlled using resistors, and when the current is constant the potential difference at the terminals is a constant. So, resistors are common components of any electrical circuit. Resistors are made with different materials with different tolerances for many applications.
What is the difference between Resistance and Resistor?
• The resistance is a property of a material to oppose the flow of electric current.
• The resistor is an electrical circuit component with a fixed resistance value that used to control current through the element or the potential difference across the element.