A coil-design worksheet lists four claims about self and mutual inductance. Pick the option that names every correct claim.

• I. The SI unit of inductance, the henry, equals one weber per ampere.
• II. For two long coaxial solenoids, the mutual inductance of the first with respect to the second equals that of the second with respect to the first.
• III. The self-induced emf in a coil opposes a rise in current but does not oppose a fall in current.
• IV. Inserting a soft-iron core into a solenoid increases its self-inductance.