Define capacitive reactance. Write its S.I. unit.
State which of the two a capacitor or an inductor, tends to become SHORT when the frequency of the applied alternating voltage has a high value.
Why is the use of ac voltage preferred over dc voltage ? Give two reasons.
A device ‘X’ is connected to an ac source V = V₀ sin(ωt). The variation of voltage, current and power in one complete cycle is shown in the following figure.
(i) Which curve shows power consumption over a full cycle?
(ii) Identify the device ‘X’.
Why is choke coil needed in the use of fluorescent tubes with ac mains ?
For an ideal conductor, connected across a sinusoidal ac voltage source. State which one of the following quantity is zero :
(i) Instantaneous power
(ii) Average power over full cycle of the ac voltage source.
Define ‘Wattless current’.
In a series LR circuit = R and power factor of the circuit is P₁. When capacitor with capacitance C such that = is put in series, the power factor becomes P₂. Calculate P₁ / P₂.