Question

Define resistance. state the factors on which it depends.

Answer 1

Resistance is the characteristic of a material which opposes the flow of electric current.
It depends on : 

i) Length of the conductor (l) : R is directly proportional to "l" 
ii) Area of cross -section (A) : R is inversely proportional to "A" 
iii) Nature of the material
iv) Temperature 

From i) and ii) , R is directly proportional to "l/A" 
=> R = rho * l/A
rho = Resistivity of a material
Resistivity depends only on the nature of the material

So, if the length is doubled of a conductor, the nature of the material will not be affected and hence, resistivity will not be changed. 

Answer 2

The property of a conduct to oppose the flow of charge is known as resistance.
Or,
The opposition offered to the flow of electrons by the conductor due to collisions between the ions and the electrons is known as resistance.

The resistance of a conductor depends on many facotrs:
1)it is directly proportional to the length of the conductor.
2)It is inversely proportional to the area of cross-section of the conductor.
3)directly proportional to the temperature of the conductor.
4)depends upon the material of the conductor.