Factors that affect the resistance of a conductor

In general, assuming temperature of a conductor is constant, the resistance of a conductor is affected by

1) length (L) – [L increases, R increases]

2) cross-sectional area (A) – [A increases, R decreases]

3) resistivity (p) = [p increases, R increases]

As R is directly proportional to L and p, and is inversely proportional to A,

R = pL/A

MCQ questions from Olevel

When radius or diameter is three times larger, cross-sectional area does not increase by three times!!

Refer to this example: 2018PPp1q31

There are times when using the formula is more appropriate.