For the Y-network shown in the figure, the value of R₁ (in Ω) in the equivalent ∆ -network is ________.

In the circuit shown in the figure, the value of node voltage V₂ is

In the circuit shown in the figure, the angular frequency $$\omega$$ (in rad/s), at which the Norton equivalent impedance as seen from terminals b-b' is purely resistive, is _______.

A series RC circuit is connected to a DC voltage source at time t = 0. The relation between the source voltage V_S, the resistance R, the capacitance C, and the current i(t) is given below: $$$V_{s\;}=\;Ri(t)+\frac1c\int_0^ti(u)du$$$ Which one of the following represents the current f(t)?