A solenoid of one metre length and 3.55 cm inner diameter carries a current of 5 A . If the solenoid consists of five closely packed layers each with 700 turns along its length, then the magnetic field at its centre is

The work done in rotating a bar magnet which is initially in the direction of a uniform magnetic field through $45^{\circ}$ is $W$. The additional work to be done to rotate the magnet further through $15^{\circ}$ is

When a current of 4 mA passes through an inductor, if the flux linked with it is $32 \times 10^{-6} \mathrm{Tm}^2$, then the energy stored in the inductor is