Explanation: \( \text{Hints: } \Delta \beta = 10 \log_{10}\left(\frac{I_1}{I_2}\right) \) \(\text{Solve: } 1 = 10 \log_{10}\left(\frac{I_1}{I_2}\right) \implies 0.1 = \log_{10}\left(\frac{I_1}{I_2}\right)\) \(\implies 10^{0.1} = \frac{I_1}{I_2} \implies I_2 = \frac{I_1}{10^{0.1}} = 0.79 I_1\) \(\therefore I_2 = I_1 - 0.21 I_1 = I_1 (1 - 0.21) = I_1 - 21\% I_1\) \(\text{Ans. (E)}\)