A lamp is connected in series with a capacitor. Predict your observation for dc and ac connections. What happens in each if the capacitance of the capacitor is reduced ?
When a dc source is connected to a capacitor, the capacitor gets charged and after charging, no current flows in the circuit and the lamp will not glow. There will be no change even if C is reduced.With an ac source, the capacitor offers capacitive reactance and the current flows in the circuit.Consequently the lamp will shine. Reducing C will increase the reactance and the lamp will shine less brightly than before.
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.
Show that in the free oscillations of an LC circuit, the sum of energies stored in the capacitor and the inductor is constant in time.
In electric arc furnace Cu or Iron is melted due to variation of
(a) current
(b) magnetic field
(c) voltage
(d) electric field
Show that the current leads the voltage in phase by in an ac circuit containing an ideal capacitor.
Obtain the expression for the energy density of magnitude field B produced in the inductor.
In series R-L-C circuit, quality factor can be improved by
(a) decreasing L
(b) increasing C
(c) decreasing R
(d) decreasing R & L
Calculate the amount of work done to dissociate a system of three charges 1 mC, 1 mC and – 4 mC placed on the vertices of an equilateral triangle of side 10 cm.
Two cells of emfs 1.5 V and 2.0 V having internal resistances 0.2Ω and 0.3Ω respectively are connected in parallel. Calculate the emf and internal resistance of the equivalent cell.
A battery of emf 12 V and internal resistance 2 Ω is connected to a 4 Ω resistor as shown in the figure.
Draw a plot showing the variation of (i) electric field (E) and (ii) electric potential (V) with distance r due to a point charge Q.
Five charges, q each are placed at the corners of a regular pentagon of side a.
(i) What will be the electric field at O if the charge from one of the corners (say A) is removed ?
(ii) What will be the electric field at O if the charge q at A is replaced by - q ?
A network of resistors is connected to a 16 V battery with internal resistance of 1 Ω, as shown in the following figure. Compute the equivalent resistance of the network.
A small metallic sphere carrying charge +Q is located at the centre of a spherical cavity in a large uncharged metallic spherical shell. Write the charges on the inner and outer surfaces of the shell. Write the expression for the electric field at the point P1.