⚡ Electrical Engineering Solved MCQs with Answers

Practice 757 approved ⚡ Electrical Engineering questions with verified answers from the 🛠️ Engineering Essentials subject for Pakistan exams.

757 solved MCQs

The primary winding of a power transformer should always beAnswer: Fused A transformerAnswer: steps up or down ac voltages The primary of a transformer is connected to a 6 V battery. The turns ratio is 1:3 and the secondary load, RL, is 100 Ω. The voltage across the load isAnswer: 0 V To step 120 V ac up to 900 V ac, the turns ratio must beAnswer: 7.5 When a 200 Ω load resistor is connected across the secondary winding of a transformer with a turns ratio of 4, the source "sees" a reflective load ofAnswer: 12.5 Ω In a certain transformer, the input power to the primary is 120 W. If 8.5 W are lost to the winding resistance, what is the output power to the load, neglecting any other issues?Answer: 111.5 W When a 6 V battery is connected across the primary of a transformer with a turns ratio of 8, the secondary voltage isAnswer: 0 V What is the coefficient of coupling for a transformer in which 4% of the total flux generated in the primary does not pass through the secondary?Answer: 0.96 A transformer has a 1:6 turns ratio and a secondary coil load resistance of 470 Ω. The load resistance as seen by the source isAnswer: 13 Ω In the complex plane, the number 14 – j5 is located in theAnswer: fourth quadrant Point +4 on the complex plane isAnswer: 4 units right of the origin on the real axis A 470 Ω resistor and a 0.2 μF capacitor are in parallel across a 2.5 kHz ac source. The admittance, Y, in rectangular form, isAnswer: 2.12 mS + j3.14 mS A positive angle of 30° is equivalent to a negative angle ofAnswer: –330° In a series RC circuit, 12 V(rms) is measured across the resistor and 15 V(rms) is measured across the capacitor. The rms source voltage isAnswer: 19.2 V A 6 kHz sinusoidal voltage is applied to a series RC circuit. The frequency of the voltage across the resistor isAnswer: 6 kHz The voltages in Problem 4 are measured at a certain frequency. To make the capacitor voltage greater than the resistor voltage, the frequencyAnswer: must be decreased In the complex plane, the number 4 + j3 is located in theAnswer: first quadrant When the frequency of the source voltage decreases, the impedance of a parallel RC circuitAnswer: Increases A 47 Ω resistor and a capacitor with a capacitive reactance of 120 Ω are in series across an ac source. What is the circuit impedance, Z?Answer: 129 Ω What is the value of the hypotenuse of a right triangle whose sides are 12 and 18?Answer: 21.63 The complex number 6 + j6 is equivalent toAnswer: 8.48<45° In a parallel RC circuit, there is 100 mA through the resistive branch and 100 mA through the capacitive branch. The total rms current isAnswer: 141 mA An ac circuit consists of a resistor and a capacitor. To increase the phase angle above 45°, the following condition must exist:Answer: R < X꜀ What is the angular difference between +j4 and –j4?Answer: 180° A resistor and a capacitor are in series across a 20 V ac source. Circuit impedance is 4.33 kΩ. Current flow in the circuit isAnswer: 4.6 mA For a certain load, the true power is 150 W and the reactive power is 125 VAR. The apparent power isAnswer: 195.2 W When the frequency of the voltage applied to a series RC circuit is increased, the phase angleAnswer: decreases In a series RC circuit, when the frequency and the resistance are halved, the impedanceAnswer: cannot be determined without values A 2 kΩ resistor is in series with a 0.015 μF capacitor across a 15 kHz ac source. What is the magnitude of the total impedance and the phase angle?Answer: 2121 Ω and θ = –19.5° A 12 kΩ resistor is in series with a 0.02 μF capacitor across a 1.2 kHz ac source. If the current is expressed in polar form as I = 0.3<0° mA, what is the source voltage expressed in polar form?Answer: 4.11 V