When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Calculate the value of the resistance of the resistor.

What is Ohm's law? Explain how it is used to define the unit of resistance.

What is meant by the "resistance of a conductor"? Write the relation between resistance, potential difference and current.

Define the of resistance (or Define the unit "ohm").

What happens to the resistance as the conductor is made thinner?