Question

The resistance of a metallic conductor:
A.Increase with rise in temperature
B.Decrease with rise in temperature
C.Remains unchanged with change in temperature
D.Becomes zero at extremely high temperature

Answer 1

Hint: First know the definition of resistance which says it is the obstruction offered to the flow of electrons between two ends of a conductor.

Complete step by step solution:
As the length of the wire increases, the resistance too will increase. The greater the length of the wire greater will be the number of collisions between the free electrons and the metal ions thus resulting in a greater resistance.
When the temperature of a metallic conductor increases, so does the velocity of free electrons causing an increase in the amplitude of vibration of these electrons.
Resistance of a metallic conductor increases with the increase (or rise) in temperature, because the temperature coefficient of conductors is positive in nature hence resistance is directly proportional to the temperature.
Therefore, the correct option is option (a).

Additional information:
Before understanding what resistance is, it is necessary to understand a bit about current and its meaning. Basically, a flow of current in a material consists of a movement of electrons in one direction. There are free electrons moving about randomly within the structure of the object.
Resistance is therefore, the hindrance to the flow of electrons in a material. While a potential difference across the conductor encourages the flow of electrons, resistance opposes it. The rate at which charge flows between two terminals is a combination of these two factors.

Note: Before being able to solve the sum students need to understand the basic concepts of resistance and also its effects due to length, temperature and other factors.