a) Define self inductance of a coil. [1] b) A current from A to B is increasing in magnitude. What is the direction of induced current, if any, in the loop as shown in figure? Justify. [2] [figure…

a) Self‑inductance of a coil

Self‑inductance $L$ is the proportionality constant between the magnetic flux linkage $\Phi$ of a coil and the current $I$ that produces it:
$$L=\frac{\Phi }{I}\text{(H)}$$

b) Direction of induced current

The current from point A to B is increasing.
According to Lenz’s law, the induced emf will oppose the change in flux.
Hence the induced current must flow from B to A so that its magnetic field opposes the increase.

flowchart TD
    A["A"] -->|"Increasing current"| B["B"]
    B -->|"Induced current"| A

c) Self‑inductance calculation

Given

• Number of turns $N=100$ (not needed for $L$ directly)
• Current $I=2\text{A}$
• Flux through the coil $\Phi =5\times 10^{-3}\text{Wb}$

$$L=\frac{\Phi }{I}=\frac{5\times 10^{-3}\text{Wb}}{2\text{A}}=2.5\times 10^{-3}\text{H}$$

$$\boxed{\text{L = }2.5\times 10^{-3}\text{H}}$$