Electromagnetic Induction and Alternating Currents: JEE Main 2022 Physics question

A coil of inductance 1 H and resistance $100 \,\Omega$ is connected to a battery of 6 V. Determine approximately : (a) The time elapsed before the current acquires half of its steady - state value. (b) The energy stored in the magnetic field associated with the coil at an instant 15 ms after the circuit is switched on. (Given $\ln 2=0.693, \mathrm{e}^{-3 / 2}=0.25$)