advertisement8. What happens to the capacitor when the capacitor voltage isequal to the source voltage?a) The charging phase of the capacitor is overb) The discharging phase of the capacitor is overc) The capacitor is switched offd) The capacitor is switched onView Answer

Answer: cExplanation: When the capacitor voltage is equal to the sourcevoltage, it means that all the charges have moved from one plateof the capacitor to the other. Hence the capacitor is fully chargedand we say it gets switched off.9. A capacitor is charged to a voltage of 400V and has aresistance of 20ohm. Calculate the final value of charging current.a) 10Ab) 0Ac) Infinityd) 20AView AnswerAnswer: bExplanation: When the capacitor is charging, the final voltage ofthe capacitor becomes equal to the voltage of source. Hence, thecurrent becomes equal to zero.Basic Electrical Engineering Questions and Answers – Growth andDecayThis set of Basic Electrical Engineering Multiple Choice Questions& Answers (MCQs) focuses on “Growth and Decay”.1. The charging time constant of a circuit consisting of a capacitoris the time taken for the charge in the capacitor to become__________ % of the initial charge.a) 33b) 63c) 37d) 36View AnswerAnswer: bExplanation: We know that: Q=Q0(1-e-t/RC).When RC=t, we have: Q=Q0(1-e-1) = 0.63*Q0.

Hence the time constant is the time taken for the charge in acapacitive circuit to become 0.63 times its initial charge.2. The discharging time constant of a circuit consisting of acapacitor is the time taken for the charge in the capacitor tobecome __________ % of the initial charge.a) 33b) 63c) 37d) 36View AnswerAnswer: cExplanation: We know that: Q=Q0(1-e-t/RC).When RC=t, we have: Q=Q0(1-e-1) = 0.37*Q0.Hence the time constant is the time taken for the charge in acapacitive circuit to become 0.37 times its initial charge.3. A circuit has a resistance of 2 ohm connected in series with acapacitance of 6F. Calculate the charging time constant.a) 3b) 1c) 12d) 8View AnswerAnswer: cExplanation: The charging time constant in a circuit consisting ofa capacitor and resistor in series is the product of the resistanceand capacitance = 2*6 = 12.4. A circuit has a resistance of 5 ohm connected in series with acapacitance of 10F. Calculate the discharging time constant.a) 15b) 50c) 5

d) 10View AnswerAnswer: bExplanation: The discharging time constant in a circuit consistingof a capacitor and resistor in series is the product of theresistance and capacitance = 5*10 = 50.5. What is the value of current in a discharging capacitive circuit ifthe initial current is 2A at time t=RC.a) 0.74Ab) 1.26Ac) 3.67Ad) 2.89AView AnswerAnswer: bExplanation: At time t=RC, that is the time constant, we knowthat the value of current at that time interval is equal to 63% ofthe initial charge in the discharging circuit. Hence, I = 2*0.63 =1.26A.6. What is the value of current in a charging capacitive circuit ifthe initial current is 2A at time t=RC.

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