Question

Specific resistance of all metals is mostly affected by
A. volume
B. pressure
C. temperature
D. magnetic field

Answer 1

Hint:A material's electrical resistivity, which determines how effectively it resists electric current, is one of its essential properties. A material that readily allows electric current has a low resistance. Resistivity is a material property. It is independent of dimensions like length or cross-sectional area. It just depends on the conditions like temperature.

Formula Used:
The formula of resistivity is,
\[\rho = {\rho _o}\left( {1 + \alpha \,\Delta T} \right)\]
where \[\alpha \] is the temperature coefficient of resistance, \[{\rho _o}\] is resistivity at a certain temperature, \[\Delta T\] is the change in temperature from that temperature.

Complete step by step solution:
Electrical resistivity is a measurement of a material's degree of resistance to current flow. The SI unit for electrical resistivity is the ohm metre \[\left( {\Omega m} \right)\]. It is frequently represented by the Greek letter rho. Materials that easily transmit current and have a low resistance are called conductors. Insulators have a high resistance and do not conduct electricity.

The force exerted on a body per square inch is referred to as pressure. It has no impact on the particular resistance. The degree of illumination is an approximate indicator of light intensity, which has relatively little bearing on temperature and specific resistance.

The magnetic force per unit charge at a place is known as the magnetic field. It plays no part in any particular resistance. The effect of temperature on specific resistance (or resistivity) is given by the formula:
\[\rho = {\rho _o}\left( {1 + \alpha \,\Delta T} \right)\]
As the temperature of a conductor rises, its resistivity also rises and the conductor's relaxation period shortens.

Hence, option C is the correct answer.

Note: It is believed that metals or conductors have a positive coefficient of temperature. The result is a positive value of \[\alpha \]. With a temperature increase of about 500 K, the resistivity rises linearly for the majority of metals which makes it clear that specific resistance is highly affected by the change in temperature.