Advertisements
Advertisements
Question
An ac circuit consists of a series combination of circuit elements X and Y. The current is ahead of the voltage in phase by `pi/4`. If element X is a pure resistor of 100 Ω,
(a) name the circuit element Y.
(b) calculate the rms value of current, if rms of voltage is 141 V.
(c) what will happen if the ac source is replaced by a dc source
Advertisements
Solution
(a) We have,
Φ = π/4
tan Φ = 1
`tanphi = "Reactance"/"Resistance"`
Reactance = Resistance
Y = 100 Ω
As, ϕ > 0°, means voltage ahead of current Hence element Y is an Inductor.
(b)
`"R.m.s value of current" = "R.m.s value of voltage"/"Impedance"`
`"i"_"Rms" = 141/sqrt((100)^2+ (100)^2)`
`"i"_"Rms" = 141/(100sqrt2) = 141/(100 xx 1.41)`
iRms = 1 A
(c) If the Ac is Replace by DC, then the Inductor will behave as a short circuit, and the circuit will be purely Resistive.
APPEARS IN
RELATED QUESTIONS
A capacitor 'C', a variable resistor 'R' and a bulb 'B' are connected in series to the ac mains in circuit as shown. The bulb glows with some brightness. How will the glow of the bulb change if (i) a dielectric slab is introduced between the plates of the capacitor, keeping resistance R to be the same; (ii) the resistance R is increased keeping the same capacitance?
A cylindrical capacitor has two co-axial cylinders of length 15 cm and radii 1.5 cm and 1.4 cm. The outer cylinder is earthed and the inner cylinder is given a charge of 3.5 µC. Determine the capacitance of the system and the potential of the inner cylinder. Neglect end effects (i.e., bending of field lines at the ends).
Figure 4 below shows a capacitor C, an inductor L and a resistor R, connected in series
to an a.c. supply of 220 V
Calculate:
1) The resonant frequency of the given CLR circuit.
2) Current flowing through·the circuit.
3) Average power consumed by the circuit.
The plates of a parallel-plate capacitor are given equal positive charges. What will be the potential difference between the plates? What will be the charges on the facing surfaces and on the outer surfaces?
The following figure shows two capacitors connected in series and joined to a battery. The graph shows the variation in potential as one moves from left to right on the branch containing the capacitors.
Find the charges on the four capacitors of capacitances 1 μF, 2 μF, 3 μF and 4 μF shown in the figure.
The figure shows a network of five capacitors connected to a 100 V supply. Calculate the total energy stored in the network.
Three capacitors each of 4 µF are to be connected in such a way that the effective capacitance is 6µF. This can be done by connecting them:
Capacitors connected in series have ______
