Electromagnetic Waves: JEE Main 2025 Physics question

Due to presence of an em-wave whose electric component is given by $E = 100\sin(\omega t - kx)$ N C$^{-1}$, a cylinder of length 200 cm holds certain amount of em-energy inside it. If another cylinder of same length but half diameter than previous one holds same amount of em-energy, the magnitude of the electric field of the corresponding em-wave should be modified as