What value of R is needed with a 0.05 μF capacitor for an RC time constant of 0.02 sec?
A400 Ω
B400 kΩ
C400 MΩ
D400 GΩ
#42📜 EE Pre-Board March 2013📘 PowerhouseEasy
The time constant of a series RL circuit Is equal to _____?
AL/R
BR/L
CRL
D1/RL
#43📜 EE Pre-Board March 2013📘 PowerhouseEasy
A capacitor of 100 micro farad is connected in series with a resistance of 1000 ohms. The time constant of the circuit is
A1 sec
B0.01 sec
C0.1 sec
D0.001 sec
#44📜 EE Pre-Board March 2013📘 PowerhouseEasy
A coil has a resistance of 5 ohms and inductance of 1 H. At t = 0 it is connected to a 2 V battery. Find the rate of rise of current when i = 0.2 ampere.
A3 A/sec
B2 A/sec
C1 A/sec
D0.5 A/sec
#45📜 EE Pre-Board March 2013📘 PowerhouseEasy
Calculate the time taken by the capacitor of 1 μF and in series with a 1 MΩ resistance to be charged up to 80% of the final value.
A0.8 sec
B1.61 sec
C2.12 sec
D1.98 sec
#46📜 EE Pre-Board August 2013📘 PowerhouseMedium
A series RL circuit is connected across a dc source through a switch. Three milliseconds after the switch is closed, the voltage across the inductance is 20 V, and it drops to 5 V after 25 ms. If R = 100 ohms, find L. Assume at t = 0, i = 0.
A1.59 H
B1.30 H
C1.22 H
D1.25 H
#47📜 EE Pre-Board March 2014📘 PowerhouseHard
A 100 μF capacitor initially charged to 24 V is discharged across a series combination of a 1 kΩ resistor and a 200 μF capacitor. Find the current after 1 sec.
A7.24 nA
B7.34 nA
C8.43 nA
D8.84 nA
#48📜 EE Pre-Board August 2014📘 PowerhouseEasy
An inductance of 40 mH is connected in series with 300 ohms resistance, At t=0, the energy stored is 0.96 microjoule. Find the current at t=0.
A\(0.44 \times 10^{-3}\) A
B\(0.22 \times 10^{-3}\) A
C\(13.86 \times 10^{-3}\) A
D\(6.93 \times 10^{-3}\) A
#49📜 EE Pre-Board August 2014📘 PowerhouseEasy
A coil of inductance 10 H and resistance 2 ohms is supplied at 20 v, Find the average emf induced when the circuit is opened if the current fails to zero in 0.5sec.
A20V
B10V
C100V
D200V
#50📜 EE Pre-Board August 2014📘 PowerhouseMedium
A 2 μF capacitor with an initial charge of 100 μC is connected across a 100 Ω resistor at t = 0. Calculate the time in which the transient voltage across the resistor drops from 40 to 10 volts.
A27.7 ms
B0.277ms
C2.77ms
D277ms
#51📜 EE Pre-Board August 2014📘 PowerhouseEasy
Inductance affects the direct current flow at the time of
Aturning on and off
Boperation
Cturning on
Dturning off
#52📜 EE Pre-Board March 2015📘 PowerhouseEasy
A time of 10 milliseconds is required for the current on a series RL dc circuit to reach 90% of its final steady state value. What is the time constant in seconds for the circuit?
A3.39 ms
B4.34 ms
C3.86 ms
D4.25 mS
#53📜 EE Pre-Board March 2015📘 PowerhouseMedium
A 1.5 MΩ resistor is connected in series with a 20 μF capacitor. The voltage source is 120 volts dc. Determine the current at t = 10 seconds after the switch is closed.
A80 μA
B63.85 μA
C32.64 μA
D57.32 μA
#54📜 EE Pre-Board March 2015📘 PowerhouseEasy
The capacitor in a series RC circuit at steady state is:
AOpen circuit
BShort circuit
CTransient circuit
DCoupled circuit
#55📜 EE Pre-Board August 2015📘 PowerhouseEasy
A capacitor is charged by a dc source through a resistor of one megohm. If in one second, the potential difference across capacitor reaches 80% of its final value, calculate its capacitance.
A0.321μF
B0.421μF
C0.512μF
D0.621μF
#56📜 EE Pre-Board March 2016📘 PowerhouseMedium
A capacitor of 40 μF capacitance in series with 2,000 ohms is suddenly connected across a 200-volt source. What is the energy stored in the capacitor after 0.04 sec?
A0.124 J
B0.241 J
C0.412 J
D2.41 J
#57📜 EE Pre-Board March 2016📘 PowerhouseEasy
A current of 20 A is flowing in an RL series circuit the instant before the switch is opened. If R = 10 Ω and L = 10 H, find the current after 3 seconds have elapsed.
A1 A
B2 A
C3 A
D4 A
#58📜 EE Pre-Board March 2017📘 PowerhouseEasy
At steady state in an RC circuit, the capacitance will act as __________.
Aopen circuit
Bshort circuit
Ctransient circuit
Dcoupled circuit
#59📜 EE Pre-Board August 2017📘 PowerhouseMedium
The current in a coil decays as follows: when t = 0.002 s the current is 10 mA; when t = 0.006 s the current drops to 4 mA. The time constant of the coil is _______.
A2.18 ms
B4.36 ms
C8.72 ms
D6.00 ms
#60📜 EE Pre-Board August 2017📘 PowerhouseEasy
A capacitor of 0.1 μF capacitance is charged to a potential difference between plates of 100 V and is discharged through a resistor of 1 megohm. Calculate the initial rate of decay of the capacitor voltage.