Importance and application of Resistance and Conductance in Circuits

Resistance

We define resistance as the opposition a substance offers to the flow of electric current.

First, a resistor is a passive component. Specifically, designers create it to regulate current. In simple terms, it impedes electrons; as a result, electrical energy converts into heat. Consequently, this opposition controls electricity. Therefore, resistors are essential. In addition, they serve many functions. For example, they divide voltage. Similarly, they limit current. Thus, they prevent damage. As a result, they ensure stability. Moreover, they protect components. Ultimately, they enhance reliability. Furthermore, these devices maintain efficiency. In fact, modern circuits depend on them. Specifically, they manage energy flow. However, they must be chosen carefully. Because of this, engineering precision is required. In conclusion, resistors are vital. Indeed, they are the backbone of electronics. Clearly, their role is indispensable. Consequently, understanding them is key. Finally, they remain fundamental tools for every electrical engineer.

Free electrons create current as they flow through a substance. The atoms and molecules in the material obstruct this flow and create resistance. Metals like silver, copper, and aluminium allow electrons to pass easily and act as conductors. On the other hand, materials such as glass, rubber, mica, and dry wood block electron flow and function as insulators.

Note that resistance creates electrical friction, which generates heat as electric current flows. The moving electrons collide with the atoms or molecules in the substance, and each collision releases a small amount of heat.

Unit of resistance;The practical unit of resistance is the ohm, represented by the symbol Ω.

There is another way of defining ohm.

A wire has a resistance of 1 ohm if it releases 1 joule of energy (or develops 0.24 calorie of heat) when a current of 1 ampere flows through it for 1 second.

A little reflection shows that second definition leads to the first definition. Thus 1 A current flowing for 1 second means that total charge flowing is Q = I × t = 1 × 1 = 1 coulomb. Now the charge flowing between A and B (See above Figure) is 1 coulomb and energy released is 1 joule (or 0.24 calorie). Obviously, by definition, p.d. between A and B should be 1 volt.

Factors Upon Which Resistance Depends

Specific Resistance or Resistivity

Hence specific resistance of a material is the resistance offered by 1 m length of wire of material having an area of cross-section of 1 `m^2`.

Figure 1

Figure 2

 

Specific resistance can also be defined in another way.Take a cube of the material having each side 1 m.Considering any two opposite faces, the area of cross-section is 1 `m^2` and length is 1 m

[See Fig. 2] i.e. l = 1 m, a = 1 `m^2`

Hence specific resistance of a material may be defined as the resistance between the opposite faces of a metre cube of the material.

Unit of resistivity. We know R = `frac{rho l}a` or ρ = `frac{Ra}l`

• If the length is measured in metres and area of cross-section in `m^2`,then unit of resistivity will be ohm-metre (Ω m).

The reader may note that the resistivity of metals and alloys is very small. Therefore, these materials are good conductors of electric current. In contrast, the resistivity of insulators is extremely large. As a result, these materials hardly conduct any current. Furthermore, scientists categorize an intermediate class of materials as semiconductors.In this case, the resistivity of these substances lies between that of conductors and insulators. Consequently, semiconductors conduct electricity under certain conditions but not as freely as metals.

Conductor

Whereas resistance of a conductor is the opposition to current flow, the conductance of a conductor is the inducement to current flow.

Conductance is crucial for evaluating electrical circuits, as it indicates the ease of electricity passing through a conductor. High conductance materials facilitate current flow, while low conductance materials obstruct the flow of electricity.

The SI unit of conductance is mho (i.e., ohm spelt backward). These days, it is a usual practice to use siemen as the unit of conductance. It is denoted by the symbol S.

Conductivity

Applications and Importance of Conductors

A conductor is a material that allows electricity or heat to pass through it easily. Conductors are essential in daily life and in many industries. Here are the main points explaining their importance and applications:

Importance of Conductors

1. Transmission of Electricity

Conductors make it possible to carry electric current from power stations to homes, schools, and industries.

2. Efficient Energy Transfer

Good conductors reduce energy loss during transmission, improving efficiency and saving power.

3. Safety in Electrical Systems

Proper conducting materials ensure stable current flow and reduce the risk of overheating or electrical failure.

4. Foundation of Modern Technology

Almost every electronic device depends on conductors to function properly.

Applications of Conductors

1. Electrical Wiring

Metals like copper and aluminum are widely used in wiring for homes, buildings, and power lines.

2. Electronic Devices

Conductors are used in circuits, mobile phones, computers, and televisions to allow current to flow between components.

3. Heating Appliances

Devices like electric irons, heaters, and kettles use conductors to generate heat through electric current.

4. Automobiles and Transportation

Vehicles use conductors in battery systems, lighting, and engine control systems.

5. Industrial Machinery

Heavy machines depend on conductive materials for power supply and control systems.

6. Communication Systems

Telephone lines, internet cables, and networking systems use conductors to transmit signals.

In short, conductors are vital for transmitting electricity and heat, and they form the backbone of electrical and electronic systems used in everyday life.