Effect of Temperature on Resistance for JEE

VSAT 2022

What is Resistance?

Resistance is often termed as the force that restricts the movement of a body, resulting in the performing ability of the body slowing down. When we value the concept in the electrical and electronics field, resistance is the defiance given by the material to access the flow of current through it. The unit of resistance is termed Ohm. The influence of temperature on resistance will vary in terms of insulator, conductor, and semiconductor. 


The electrical resistance shows potential change during the effective change in the temperature. Along with the rise in the temperature, resistance not only prioritises increasing but effectively decreases as well in some cases. Different types of materials have a significant impact on the temperature and vice-versa. Let us discuss the terms and conditions of temperature’s effect within different materials. 


Influence of Temperature on the Conductor’s Resistance Capacity

The potential or the resistance of the conductor fluctuates in accordance with several factors, such as the type of material the conductor is made up of, the actual size of the specific conductor, the ambience of the surroundings, and other elements. Temperature is another pivotal factor that channelizes the changes in the resistance of a conductor. 


The diffusion of the current along a conductor is classified as the flow of the conductor’s electrons. The fluctuation of the electrons is characterised by the induced electrical field involved inside the conductor. These involved electrical fields grow and charge potential in the conductor that facilitates the flow of electrons towards the terminal based on the opposite terminal. The temperature dependence of resistance totally depends on this above process and involves the functionality accordingly. 


The rising temperature facilitates a concussion along with the electrons of the conductors that are moving; hence the derived flow of the electrons shows the net as zero, which signifies there is the null flow of current in the field of conductor. Moreover, it has the potential for high resistance. The effect of the change of temperature depends on the various types of conductors used in the process. This makes us understand the effect of temperature on the resistance of the conductor. 


The impact of the temperature on the conductor’s resistance capacity is significantly proportional to each other. The increasing rate of temperature in the conductor fastens the resistance and restricts the flow of current or makes it difficult for the flow inside the conductor. As we have clarified in the above section, the flow of free electrons facilitates the current flow inside the conductor; hence it becomes the temperature coefficient of resistivity. 


The free-moving electrons present in the metal conductor’s discord with the various electrons present in the metal and help in generating the heat. When more heat is generated, collisions take place in a vast manner. This process becomes an obstacle to the further flow of the electrons within the conductor and brings out more resistance. This is why resistance increases with temperature. 


Influence of Temperature on the Semiconductor’s Resistance

Talking about the semiconductors, the conduction process values when the electrons shift to the conduction band straight from the valence band. The barred energy gap within the conduction band and the valence band inside the semiconductor are very small. Processing the usage of the small energy, the loosely merged electrons of the valence band can easily get access to the conduction band. 


With the application of the temperature to the materials of the semiconductor, the strengthened bond between the atoms can be deflected, and this will let the electrons shift from the valence band to the conduction band, and hence the semiconductor increases its conductivity capacity since the body’s conductivity capacity is inversely proportional to the resistance capacity. Hence, the semiconductor's resistance capacity decreases with the temperature increase. This shows that the effect of temperature on resistance or resistivity is very influential. 


Influence of Temperature on the Insulator’s Resistance Capacity

The elements of the insulators are classified as the electrons present in the insulators that are complicatedly bound closely to the nucleus, and it is quite impossible to destroy the bond. However, the barred energy gap between the valence and the conduction band is vast. So, it is nearly impossible to regulate conduction among the insulator in general conditions. 


As the temperature increases, the outermost electrons in the valence band start shaking, and this vibration decreases the strengthening capacity of the bond between the nucleus and the electrons. It gives the probability of conduction when the conduction band gets adherence to the valence band electrons. 


The increase in the temperature minimises the barred energy gap to a certain extent and starts processing the conduction. Since, at some level of temperature, insulators start adopting the characteristics of the conductor when the temperature increases. The conductivity capacity of the insulators increases along with the decrease in resistance. Hence, temperature and resistance play a crucial role in shaping the following procedure. 


Various materials that are available have the capacity of zero resistance, known as superconductors. The temperature in which the obtaining value of the material will be zero resistance is known as the critical temperature of the conductor. 


The resistivity along with the material is termed to be the measure of the resistance of that particular material of the unit cross-sectional space and the length of the unit. The S.I unit of resistivity is denoted as ohm-metre. The material’s resistivity is also known as the particular resistance of the following material. 


The following concept will make you understand the term resistivity.


Let ${{\rho }_{{{t}_{1}}}}$  and ${{\rho }_{{{t}_{2}}}}$ be the resistivity at the temperatures $t_{1}^{\circ }C$ and $t_{2}^{\circ }C$. Let ‘m’ be the slope of the linear portion of the curve.


$m=\frac{{{\rho }_{{{t}_{2}}}}-{{\rho }_{{{t}_{1}}}}}{{{t}_{2}}-{{t}_{1}}}$

${{\rho }_{{{t}_{2}}}}={{\rho }_{{{t}_{1}}}}+m\left( {{t}_{2}}-{{t}_{1}} \right)$

${{\rho }_{{{t}_{2}}}}={{\rho }_{{{t}_{1}}}}\left[ 1+\frac{m}{{{\rho }_{{{t}_{1}}}}}\left( {{t}_{2}}-{{t}_{1}} \right) \right] $

 

The ratio $\frac{m}{{{\rho }_{{{t}_{1}}}}}$ is termed as the temperature coefficient of resistivity at $t_{1}^{\circ }C$ and is almost equal to ${{\alpha }_{1}}$ .

${{\rho }_{{{t}_{2}}}}={{\rho }_{{{t}_{1}}}}\left[ 1+{{\alpha }_{1}}\left( {{t}_{2}}-{{t}_{1}} \right) \right]$ 


The proportionality constant of the above outcome of the resistance is termed as the resistivity of the material. The resistivity hinges on the material of the shape, body, size of the body, the significant temperature, and others. 


Generally, the conductor has a small resistivity capacity. But the increasing nature of the temperature will fuel the growth of resistivity of the conductor. Initially, the insulator involves a massive resistivity, but as the temperature goes high, the resistivity of the insulators diminishes accordingly. Hence, the resistivity capacity of the semiconductor material is inversely proportional to the body’s temperature. This is because the resistance changes with temperature. 


The metal’s resistivity gets accelerated linearly with the increase in the temperature along with the slope. 

$m=\frac{{{\rho }_{{{t}_{2}}}}-{{\rho }_{{{t}_{1}}}}}{{{t}_{2}}-{{t}_{1}}}$ 


To gather insight into the change in resistance followed by the temperature element, the temperature coefficient of resistivity is considered. The temperature coefficient is termed to be the change in the resistance within a body with the interpretation of per degree centigrade temp. Considering the interpretation of the resistance with the temperature, the coefficient is classified as the positive temperature and negative temperature coefficient. 


Conclusion

When the relation shows direct proportionality, we can see the growing temperature, known as the positive temperature coefficient. Accordingly, if the body’s resistance decreases along with the temperature increase, the temperature coefficient is termed as the negative temperature coefficient. Here we discussed the specific features of the materials that change according to the shift of the temperature. The resistivity of the metals, conductors, semiconductors and insulators changes as per the temperature effects.

FAQs on Effect of Temperature on Resistance for JEE

1. How come the temperature influences the resistance and resistivity?

The rise in the temperature makes the number of phonons increase, and accordingly, the electrons and protons will tend to collide with each other. Hence, when the temperature rises, resistance also goes up. If we value some other materials, then resistivity is considered to be a linear function of the temperature. The resistivity of the conductor also increases when the temperature rises. The vigorous deflection of the ions makes the process more effective, and hence the temperature behaves to be influencing the behaviour of resistance and resistivity.

2. What is the impact of temperature on the resistivity capacity of different materials?

The resistivity capacity of the material is directly proportional to the temperature. If we talk about the different materials, then the reaction of the temperature varies in conductor, semiconductor, and electrolytes or insulators. In conductors, the resistivity capacity increases along with the temperature when the collision among the free electrons happens vigorously. 


In semiconductors, the increasing temperature diminishes the resistivity quality. When it comes to the electrolytes or the insulators, the increasing temperature makes the resistivity decrease considerably due to the decrease in viscosity. The influence of the temperature casts distinctive characteristics on different materials.

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