A capacitor is used in the primary circuit of
an induction coil.
(c) An applied voltage
signal consists of a superposition of a dc voltage and an ac voltage of
high frequency. The circuit consists of an inductor and a capacitor in series.
Show that the dc signal will appear across C and the ac signal across L.
(d) A choke coil in
series with a lamp is connected to a dc line. The lamp is seen to shine
brightly. Insertion of an iron core in the choke causes no change in the lamps
brightness. Predict the corresponding observations if the connection is to
an ac line.
(e) Why is choke coil
needed in the use of fluorescent tubes with ac mains? Why can we not use
an ordinary resistor instead of the choke coil?