Question

Name the different methods of finding unknown resistance

Answer 1

There are different methods to measure a resistance .But there capacities are variable . Some are used for measuring low some are for high resistance .
These methods includes
the Ohmmeter method (using ohmmeter), Wheat-stone bridge method, using ammeter - voltmeter. 
for high resistance measurement methods like "megger method" , direct deflection method and loss of charge method are used.
If you re measuring low resistance then "ductor ohmmeter''  and potentiometer method would be effective in using for finding it.

Answer 2

Resistance is the obstruction to the flow of electrons in a circuit.

We can classify the resistance in the following way :

Classification of Reistance :
low resistance=0.1ohm to 1 ohm

medium resistance =1ohm to low mega ohm

high resistance=0.1 megaohm to a higher range.

Different methods of finding Unknown resistance  are based on type of resistance used:

Methods for finding
 
Low resistance:
Kelvin double bridge
Ammeter -voltmeter 

Resistance For medium Resistance:
Ammeter -voltmeter method
Wheat stone bridge method
ohm meter method

Method for finding high Resistance:
Direct deflection method
loss of charge method
Megha ohm bridge method