The electric current in the circuit is given as $$i=i_{\circ}(t/T)$$. The r.m.s cm1:ent for the period t = 0 to t = T is______.

We need to find the RMS current for $$i = i_0(t/T)$$ from t = 0 to t = T.

Formula for RMS current:

$$i_{rms} = \sqrt{\frac{1}{T}\int_0^T i^2 dt}$$

$$= \sqrt{\frac{1}{T}\int_0^T i_0^2 \frac{t^2}{T^2} dt} = \sqrt{\frac{i_0^2}{T^3}\int_0^T t^2 dt}$$

$$= \sqrt{\frac{i_0^2}{T^3} \cdot \frac{T^3}{3}} = \sqrt{\frac{i_0^2}{3}} = \frac{i_0}{\sqrt{3}}$$

Therefore, the RMS current is Option 2: $$\frac{i_0}{\sqrt{3}}$$.