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An Inductor works as a ________ circuit for DC supply.
Induced voltage across an inductor is zero if the current flowing through it is constant, i.e. Inductor works as a short circuit for DC supply.
A power factor of a circuit can be improved by placing which, among the following, in a circuit?
Power factor = Real power / Apparent power = kW/kVA
By adding a capacitor in a circuit, an additional kW load can be added to the system without altering the kVA.
Hence, the power factor is improved.
Which among the following equations is incorrect?
What is the value of capacitance of a capacitor which has a voltage of 4V and has 16C of charge?
Q is directly proportional to V.
The constant of proportionality in this case is C, that is, the capacitance.
Hence Q = CV
From the relation,
C = Q/V = 16/4 = 4F
What is the total capacitance when two capacitors C1 and C2 are connected in series?
When capacitors are connected in series, the equivalent capacitance is:
1/C_{total}=1/C1 + 1/C2
therefore,
C_{total} = C1*C2 / (C1+C2)
A resistance of 7 ohm is connected in series with an inductance of 31.8mH. The circuit is connected to a 100V 50Hz sinusoidal supply. Calculate the current in the circuit.
X_{L }= 2*π*f*L = 10 ohm
Z^{2 }= (R^{2}+X_{L}^{2})
Therefore the total impedance
Z = 12.2 ohm
V = IZ
therefore,
I= V/Z = 100/12.2 = 8.2A
The equivalent circuit of the capacitor shown below is:
Due to initial condition, at t = 0 capacitor will act as a constant voltage source (at t = 0, capacitor acts as shortcircuit). Hence, option (d) is correct.
The strength of current in 1 Henry inductor changes at a rate of 1 A/sec. The magnitude of energy stored in the inductor after 3 sec is:
∴ Current in the inductor after 3 sec is:
1= 3 A
Hence, energy is stored after 3 sec:
The current and voltage profile of an element vs time has been shown in given figure. The element and its value are respectively:
Figure shown below exhibits the voltagetime profile of a source to charge a capacitor of 50 μF. The value of charging current in amperes is:
From given figure:
The equivalent capacitance across the given terminals AB is:
The charging time required to charge the equivalent capacitance between the given terminals ab by a steady direct current of constant magnitude of 10 A is given by:
Equivalent capacitance between terminals ab is:
An ac voltage of 220 V is applied to a pure inductance of 50 H. If the current is 5 A, the instantaneous value of voltage and current will be respectively given by:
Max. value of current:
Assuming voltage as the reference phasor:
The voltage and current through a circuit element is v= 100 sin (314 t + 45°) volts and i = 10 sin (314 t  45 ° ) amps.
The type of circuit element and its value will be respectively:
The phase difference between v and i is:
Since v leads i therefore, the circuit element is an inductor.
The equivalent inductance for the inductive circuit shown below at terminal “ 1  2 ” is:
Converting the internal star connected inductance to an equivalent delta, the circuit reduces as shown below.
Hence, equivalent circuit becomes as shown below.
22 docs274 tests

22 docs274 tests
