Question

(i) Distinguish between resistance and resistivity of a material.
(ii)What are the factors affecting the resistance of an electric conductor? Explain any two factors.

Answer 1

Hint:
All materials have many physical properties. One such property of a material is resistance. Resistance and resistivity are not the same and here we have to distinguish both resistance and resistivity. There are different factors that affect the resistance of a material. In the second question, we have to write the factors that affect resistance and explain any two of the factors.

Complete step by step solution:

Resistance	Resistivity
The resistance of a material can be defined as the hindrance offered by the material opposing the flow of current through it.	The resistivity of a material can be defined as resistance offered by the material per unit length.
The resistance of a material is proportional to the length of the material and inversely proportional to the area of the cross-section of the material.	The resistivity of a material is directly proportional to the product of the resistance of the material and the area of cross-section of the material and inversely proportional to the length of the material.
Resistance is represented using $R$and the expression for resistance is, $R = \rho \dfrac{l}{A}$Where $\rho $is the resistivity, $l$is the length, and $A$is the area of cross-section.	The resistivity is represented using $\rho $and is expressed as, $\rho = \dfrac{{RA}}{l}$ where, $R$is the resistance, $l$is the length, and $A$is the area of cross-section.
Resistance is measured in the units of Ohm $\left( \Omega \right)$	Resistivity is measured in the units of Ohm-meter$\left( {\Omega m} \right)$
The resistance of material will depend on the area of the material and the length of the material.	The resistivity of the material will depend on the type of material and the temperature of the material.

-There are mainly four factors that affect the resistance of a material. The factors are:
(a) The material type
(b) Length of the material
(c) Area of cross-section of the material
(d) The temperature of the material
-Material type
Different types of materials have different ranges of resistance. Some materials offer higher resistance to the flow of current. Such materials are called bad conductors. Some materials offer very low resistance to the flow of current such materials are called good conductors. Materials like wood, plastic, etc. are bad conductors. Materials like iron, copper, etc. are good conductors.
-Length of the material
As the length of the conductor increases, the current will have to travel a longer distance to reach the destination and this will increase the resistance. For shorter conductors, the current will not face much resistance as it does not have to travel a long distance.

Note:
The other two factors are also explained-
-Area of cross-section of the material
The resistance of the material decreases with the increase in the area of the material. If we consider the example of a hose through which water is flowing, the water will flow freely through a wider hose than through a narrow hose. This is the same in the case of resistance also. As the conductor becomes wider the current will flow freely with less resistance. As the conductor becomes narrower there will be more resistance.
-The temperature of the material.
When the temperature increases the kinetic energy of the particle also increases. As a result of the increase in kinetic energy, the particles will collide with each other. This collision will hinder the flow of current through the material. Thus we can say that the resistance of material will increase with the increase in temperature.