Answer to Question #53458 in Electric Circuits for manisha

Question

how the formula of resistance changes in different conditions like:
1 when mass, resistance,density of material of which wire is made and resistivity of the wire is given and we have to find diameter and length of the wire.
2 when length, diameter and resistance of wire is given and we have to find resistivity of the material of wire.
3 when resistance of wire is given and length is increased to twice its original length.and we have to calculate new resistance.
4 when a wire is stretched to reduce its diameter to half its original value and we have to find new resistance of wire.
5 when resistance of wire is given and the wire is stretched so that its length become s 3 times. assuming that there is no change in density on stretching and we have to calculate the resistance of new wire.
PLEASE ALSO GIVE REASON THAT HOW FORMULA CHANGE.