The obstruction offered to the flow of current by a wire is called :

1. current
2. potential
3. resistance
4. charge

According to Ohm's law :

1. I ∝ V
2. V/I = constant
3. V = IR
4. All of the above

The unit of conductance is :

1. volt
2. ohm
3. ohm^-1
4. ampere

Out of the following, non-ohmic resistor is :

1. nichrome
2. copper sulphate solution with copper electrodes and dil sulphuric acid.
3. solar cell
4. silver