Category: Physics Questions

Resistance is referred to as an obstacle to the electron’s flow in a material whenever the potential difference is applied across the conductor, which aids in the movement of the electrons. In contrast, resistance opposes the movement of the electron. 

Whenever the voltage is applied across a substance, an electrical current is produced, and the voltage applied across the substance is directly proportional to the current. This is represented by  

V∝I 

The proportionality constant is known as the resistivity of materials resistance. 

V=RI   

Therefore, resistance is defined as the voltage ratio applied through the substance to the current.

Well, let us take an example to understand resistance,

Think about the break time in your school, when all the students are outside the classroom, stay in the field relaxing, playing and some are sitting in groups. As the school bell rings, all get up and starts moving towards their respective classes. Well, where you are in the open field, ample children can walk together to move towards their destinations that are their respective classes.  

But when you come closer to the classroom, there is just a door allowing one or two children to move at a time as the door is narrower as compared to the corridor or, say, field. The corridor or the field has a higher resistance as compared to the classroom door. A similar concept is the movement of electrons.  

So how does this concept apply to electrical resistance?

Resistance is defined as an electrical circuit that opposes the passage of electrons. So, got it relatable, like the narrowed door limited the passage of students, the resistance opposes the passage of electrons.  

Where there is current through any material that has resistance, heat is generated by free electrons collisions and atoms. And consequently, a wire that has small resistance becomes warm where there is enough current to pass through it.  

What is the unit of resistance?

The unit of resistance is the ohm, represented by the Greek letter omega. 

Therefore, the unit of resistance is Ω.  

Resistance of different materials

1. Conductors: Conductors are materials that offer far less resistance to electrons flow. For instance, silver is a good electricity conductor, but because of its higher costs, it is not commonly used in electrical systems. Aluminum is also a good conductor that is widely used. 

1. Semiconductor: Semiconductors are materials that offer moderate resistance value. That means not very high and not very low. Germanium and silicon are the two most commonly used semiconductors.  

1. Insulators: Insulators are materials that offer very high resistance to the electron’s flow. But there are very bad electricity conductors and are mainly used to prevent current leakage. Porcelain, mica, dry wood are some excellent examples of insulators.   

What causes or reduces resistance?  

Electrical resistance has to do with the material the electrons or electricity are passing through. The more free electrons that can be tattered from the atoms, the less the resistance. The cause and reduction of resistance depend on several factors. Several factors affect resistance which in turn is responsible for the cause and reduction.   

Resistance decreases with an increase in temperature. There are four factors on which the cause and reduction of resistance depend. 

1. Length 

1. The type of material 

1. It’s the cross-sectional area 

1. The nature of the material. 

The resistance depends on the length, nature, material, and cross-sectional area of a wire.  

Do you know?  

• Thick wires have less resistance as compared to thin wires. 
• Longer wires adhere to more resistance than shorter ones. 
• Copper wires have less resistance as compared to steel wires of similar size. 

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Energy is defined as the capacity to do work and is also required to evolve life forms on earth. You must have heard about the several forms of Energy, including heat, chemical, electrical, etc. Several principles and laws govern Energy which is known as the Law of Conservation of Energy. Let us dive into the laws of conservation of Energy.

What does the Law of conservation of energy state?  

The Law of Conservation of Energy states that “Energy can neither be created nor destroyed. It may only be transformed from one form to another.” 

This states that a system always has a constant amount of Energy unless the Energy is added from outside.

While taking all forms of Energy into account, an isolated system’s total Energy always remains constant. Every form of Energy follows the Law of conservation of energy and states that “In a closed system, the total energy of a system is conserved.”

In an isolated system like the universe, if there is some energy loss in some part, then there also must be the gain of an equal amount of Energy in some other part.   

The energy amount in any isolated system is determined by: 

UT = UI + W + Q  

Where  

• UT stands for the total Energy of a system 
• UI stands for initial Energy of a system 

• Q represents the head removed or added from the system 
• W is the work done on or by the system 
  

The change in internal Energy of a system is determined by  

ΔU=W+Q  

This equation is also a statement of thermodynamics first law.   

About Energy Conservation  

Energy conservation is not only about confining the resources utilization that will finally run out. The ideal conservation method would be diminishing demand on a determined supply and enabling that supply to initiate rebuilding itself. Ample times one best way of performing this is by replacing the Energy utilized with an alternative.  

Examples of Law of Conservation of Energy  

Ample mechanical and electrical devices function on the Law of Conservation of Energy. Here are a few examples of the Law of Conservation of Energy.  

• In hydroelectric power plants, water falls over the turbines from a certain height and rotates the turbine, producing electricity. Therefore, the water’s potential Energy is converted into the turbine’s kinetic Energy that is further converted into Electrical Energy.  
• In a torch, the battery’s chemical energy is converted into an electrical one that is further converted to light and heat energy. 
• In a microphone, the sound Energy is transformed into electrical Energy. 
• In a loudspeaker, the electrical Energy is transformed to sound Energy. 

• When the fuels are burnt, the chemical Energy is then transformed into light and heat energy. 
• In a generator, mechanical Energy is transformed into electrical Energy. 
• The chemical energy from a food item is transformed to thermal Energy when it is broken down in the body and is utilized to keep it warm.

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The resistance of a filament lamp also increases when the potential difference increases as it makes the filament red hot.

The electron movement makes the kinetic energy of atoms of the filament oscillate faster and heats up the filament. 

During this process, it’s very difficult for the electrons to find a passage through the filament due to the high kinetic energy of the atoms, and the resistance increases. 

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