One henry of inductance is defined as:

• the amount of counter emf required to reduce a current to 1 A
• the amount of inductance required for generating 1 V of counter emf when the current changes at the rate of 1 A per second
• the amount of inductance required to change the frequency of a current by 1 Hz
• the number of turns of wire in an inductor multiplied by the amount of current flowing through it
• None of the above