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When the electric current passes by the conductor or any bulb, the conductor provides various current barriers, which is called the electrical resistance. R. represents the electrical resistance. Every object has electrical resistance and the conductors release the heat as the current flows through the object. In this topic, we will study the definition of Electrical resistance & various Factors Affecting Electrical Resistances.
What is electrical resistance?
An electron moving via the electric wires & loads of an external circuit experienced the resistance. The resistance is the hurdle to the flow of the charge. An electron does not move in a direct route between the terminals. It follows the zigzag pattern where the electron experiences several collisions with stable atoms in the conducting material. In other words, an electron experiences numerous hindrances during its movement from one terminal to another and it is known as electrical resistance. The SI unit to measure the electrical resistance is ohms (Ω).
According to the definition, resistance of the conductor is the ratio of potential-difference ‘V’ applied across terminals of the conductor to current ‘I’ passing by their terminals. Mathematically, formula of the electrical resistance given by:
R = V/I
(Here, ‘R’ represents Resistance)
1 Ohm = 1 Volt/ 1 Ampere = 1 V/1A
Hence, 1Ω is determined resistance of conductor via which 1A ampere of current flows by the conductor when potential difference of 1 V is applied to end terminals.
Dimensional formula for resistance: [ML2T-3A-2]
What is the significance of electrical resistance?
As a result, adding resistors to an electrical circuit to control the current flow and protect the circuit’s components is usually beneficial. Resistance is also beneficial since it allows us to protect ourselves from the potentially destructive energy of electricity.
What are the various factors that affect the electrical resistance of the conductor?
The factors that affects the electrical resistance of conductor are:-
Temperature of conducting material
Length of conductor
Material of conductor
Cross-sectional area of conductor
The temperature of conducting material
As the object’s temperature rises, the heat energy of the object also rises because of which atoms/ions the conductor begins vibrating with more frequencies and amplitudes. As free electrons start to drift towards positive terminals of the conductor, the time to relax decreases. It expands the resistance of the conductor.
Length of Conductor
Let us suppose two slabs of conductors have cross-section area ‘A’ and length ‘l’. Assume that ‘V’ is the potential difference applied through any end of conductors, and ‘I’ is the current flowing through it.
As we have read above, the resistance of the conductor is:
R = V/I
We have to place two similar conductors adjustments to each other so that the total length will become l + l = 2l. When the same potential difference is applied across both slabs, the current becomes I/2. Resistance of ordering becomes:
R’ = V/I/2 = 2V/I = 2R…..(1)
From the above equation (1), we can conclude that the resistance becomes double by doubling the length of the conductor or wire. Hence, we can say that length of the wire is directly proportional to the resistance,
R ∝ I
Characteristics of the substance
Conductors
The conductors are substances having low resistance. Copper has a low resistance but a high conductivity, due to this property it is used as a connecting wire, as we learned in prior lessons. Other metals, such as gold and silver, can conduct electricity as well. Here R stands for resistance, then G stands for conductance.
1/R = G
Insulators
Insulators are objects having a high level of resistance. The pure semiconductors have an extremely high resistance and are sandwiched between the conductor & the insulator.
Alloys
Due to the low resistance of manganin and Constantan alloys, shorter lengths are necessary to produce standard resistances for wires of a specific diameter.
Area of the Conductor
The potential difference across the ends of a conductor is applied and the current flowing through it is I/2, the resistance.
V/I/2 = 2 V/I = 2R…. (2)
Here, V= potential difference
R= resistance
Difference Between Resistance And Resistivity
Conclusion
In the above notes, we have read about the definition, derivation and examples of electrical resistance. We have discussed the factors Affecting Electrical Resistance and the difference Between Resistance And Resistivity. According to the definition,
“ When the electric current passes by the conductor or any bulb, the conductor provides various current barriers, called the electrical resistance”. It is one of the most crucial topics of physics. For better underrating and depth knowledge of the chapter, thoroughly go through the notes provided above.
