The rms value of current, as measured by an ammeter in an AC circuit, is \( I_{\text{rms}} = 10 \, \text{A} \). The peak current \( I_0 \) is related to the rms current by the formula \( I_0 = I_{\text{rms}} \cdot \sqrt{2} \). Therefore, the peak current is \( I_0 = 10 \cdot \sqrt{2} \, \text{A} \).
Final answer: \( 10\sqrt{2} \, \text{A} \)