$A$ coil and a bulb are connected in series with a $12 \,V$ direct current $(DC)$ source. $A$ soft iron core is now inserted into the coil. Then,

Which of the following is not a unit of self-inductance?

An air-cored solenoid with length $20 \, cm$,area of cross-section $20 \, cm^2$,and number of turns $400$ carries a current of $2 \, A$. The current is suddenly switched off within $10^{-3} \, s$. The average back $emf$ induced across the ends of the open switch in the circuit is (ignore the variation in magnetic field near the ends of the solenoid) ........ $V$.

$A$ long solenoid has $1500$ turns. When a current of $3.5 \, A$ flows through it, the magnetic flux linked with each turn of the solenoid is $2.8 \times 10^{-3} \, Wb$. The self-inductance of the solenoid is (in $ \, H$)

$A$ solenoid is connected to a battery so that a steady current flows through it. If an iron core is inserted into the solenoid,the current will

When current in a coil changes from $2 \ A$ to $5 \ A$ in a time of $0.3 \ s$,if the emf induced in the coil is $40 \ mV$,then the self inductance of the coil is