An iron rod is placed parallel to magnetic field intensity 2000 A/m. The magnetic flux through rod is $6 \times 10^{-4}$ wb and its cross sectional area is 3 cm$^2$. The magnetic permeability of the rod in wb/A-m is

The magnetic flux near the axis and inside the air core solenoid of length 60 cm carrying current I is $\dfrac{\pi}{2} \times 10^{-6}$ Wb. Its magnetic moment will be (cross-sectional area is very small as compared to length of solenoid, $\mu_0$ = Permeability of free space = $4\pi \times 10^{-7}$ SI unit)

If the number of turns in the coil of a moving coil galvanometer decreases, the resistance of the galvanometer,

The current flowing through the inductor of self inductance 'L' is continuously increasing at constant rate. The variation of induced e.m.f. (e) versus $\dfrac{dI}{dt}$ is shown graphically by figure