Question

Of the following, the copper conductor which has least resistance is:
1) thin, long and hot
2) thick, short and cool
3) thick, long and hot
4) thin, short and cool

Answer 1

answer is 2
r is inversely proportional to thickness, length..
more is the temperature more is the random motion hence more is the resistance ..........

Answer 2

Answer:

2) thick, short and cool

Explanation:

At a constant temperature and pressure, there are various factors which affect the resistance of a conducting wire which is discussed below:

• Length of the wire: When we increase the length of the wire, the resistance of the wire also increases and it's vice-versa. This means in order to have the least resistance, we must have a shorter wire.

• Thickness: Thickness here is understood for the area of cross-section of the wire. If the thickness of the wire increases, the resistance of the wire decreases in the same manner and decreases on increasing the thickness. This means in order to have the least resistance of the wire, we must have a thicker wire.

• Nature of material: The resistance of a wire is different for different materials of which the wire is made of. This nature of material predicts the resistivity on which the resistance is directly dependent.  

Moreover, for a particular material of the wire, the resistivity of the wire increases on increasing the temperature. So, the temperature of the wire must be least in order to have the least resistance.