ELECTRICAL CIRCUITS Multiple Choice Questions Part 3.

1 What is the temperature coefficient of the resistance Eureka?

⦁ Infinity

⦁ Negative

⦁

**Almost zero**

⦁ Positive

2 If resonant frequency is 10 kHz and quality factor is 50, then

⦁

**Bandwidth is 200 Hz**

⦁ XL = is 50,000 fi

⦁ R is 50 fi

⦁ XC = is 50,000 fi

3 The voltage lags the current by n cycle in a

⦁ Purely resistive circuit

⦁ Purely inductive circuit

⦁

**Purely capacitive circuit**
⦁ Circuit containing resistance, capacitance and inductance

4 What is the half-power bandwidth of a parallel resonant circuit which has a resonant frequency of 3.6 MHz and Q of 218?

⦁ 1.65 kHz

⦁ 16.5 MHz

⦁

**16.5 kHz**
⦁ 165 kHz

5 Which one of the following elements serves as a protection against overload?

⦁

**Fuse**
⦁ Switch

⦁ Resistor

⦁ Relay

6 What capacitance exists not through design but simply because two conducting surfaces

are relatively close to each other?

⦁ Surge

⦁

**Stray**
⦁ Natural

⦁ Normal

7 If three 100-pF capacitors are connected in series, then the total capacitance is

⦁ 300 pF

⦁ 100 pF

⦁ 50 pF

⦁

**33.3 pF**
8 An inductance of 1 mH is

⦁

**0.001 H**
⦁ 0.01 H

⦁ 0.0001 H

⦁ 0.10 H

9 The unit of elastance is

⦁ Farad

⦁

**Daraf**
⦁ Siemen

⦁ Henry

10 The farad is not equivalent to which of the following combination of units

⦁

**CV2**
⦁ C2/J

⦁ C/V

⦁ J/V2

11 In an RL series circuit,

⦁

**Current lags voltage by less than 90˚**
⦁ Current lags voltage by 180˚

⦁ Current lags voltage by 90˚

⦁ Current leads voltage by 90˚

12 In a pure capacitance,

⦁

**Current leads voltage by 90˚**
⦁ Current leads voltage by 180˚

⦁ Current lags voltage by 90˚

⦁ Current lags voltage by 180˚

13 Which of the following elements is active?

⦁ Resistor

⦁ Inductor

⦁ Capacitor

⦁

**Ideal voltage source**
14 What is the complex impedance of a circuit with an absolute resistance of 300 fi?

⦁ 0 + j 300 fi

⦁ 300 + j 90 fi

⦁ 0 – j 300 fi

⦁

**300 + j 0 fi**
15 The Q-factor of a parallel resonant circuit is also known as

⦁

**Current magnification factor**
⦁ Voltage magnification factor

⦁ Load factor

⦁ Leakage factor

16 The Q-factor of a series resonant circuit is also known as

⦁ Current magnification factor

⦁

**Voltage magnification factor**
⦁ Load factor

⦁ Leakage factor

17 An electric circuit contains

⦁ Passive elements

⦁ Active elements

⦁

**Both active and passive elements**
⦁ Reactive elements

18 What is the hot resistance of a 100 W, 220 V incandescent lamp?

⦁ 2.2 fi

⦁ 22 fi

⦁

**484 fi**
⦁ 4.84 fi

19 What is a closed path made of several branches of the network called?

⦁ Junction

⦁ Node

⦁ Terminal

⦁

**Loop**
20 The internal resistance of an ideal voltage source is

⦁ Infinite

⦁ Equal to the load resistance

⦁

**Zero**
⦁ To be determined

21 What value of R is needed with a 0.05 µF C for an RC time constant of 0.02 s?

⦁ 400 fi

⦁ 400 Mfi

⦁ 400 Gfi

⦁

**400 kfi**
22 Which of the following is the statement of Ohm’s law?

⦁ Electric current is directly proportional to both voltage and resistance

⦁

**Electric current varies directly as the voltage and inversely as the resistance**
⦁ Electrical power is directly proportional to the resistance and inversely as the current squared

⦁ Electrical power is directly proportional to both voltage squared and the resistance

23 A real current source has

⦁ Infinite internal resistance

⦁ Zero internal resistance

⦁

**Large internal resistance**
⦁ Small internal resistance

24 What is the cross-sectional are of a conductor whose diameter is 0.001 inch?

⦁ One micron

⦁ One angstrom

⦁ One steradian

⦁

**One circular mil**
25 Which of the following describes the action of a capacitor?

⦁

**Stores electrical energy**
⦁ Opposes changes in current flow

⦁ Creates a dc resistance

⦁ Converts ac to dc

26 A rheostat is a form of

⦁

**Variable resistor**
⦁ Variable capacitor

⦁ Potentiometer

⦁ Thermocouple

27 Metal tin becomes superconductor at approximately

⦁ 6 K

⦁

**3.7 K**
⦁ 5 K

⦁ 4.7 K

28 The Q-factor of a parallel resonant circuit is also known as

⦁ Voltage magnification factor

⦁

**Current magnification factor**
⦁ Gain magnification factor

⦁ Resonance magnification factor

29 What is the specific resistance of a pure silicon?

⦁ 55 fi-mm

⦁ 55 fi-m

⦁

**55 fi-cm**
⦁ 55 kfi-m

30 Capacitance increase with

⦁

**Larger plate area and less distance between plates**
⦁ Larger plate area and greater distance between plates

⦁ Smaller plate area and less distance between plates

⦁ Higher values of applied voltage

31 What is the resonant frequency of a circuit when L of 3 microhenrys and C of 40 picofarads are in series?

⦁ 14.5 kHz

⦁ 145 MHz

⦁

**14.5 MHz**
⦁ 145 kHz

32 For a triangular and sawtooth waveform the rms voltage or current equals

⦁ 0.707 times peak value

⦁

**0.577 times peak value**
⦁ 0.577 times average value

⦁ 0.707 times rms value

33 If two resistances of 9 fi and 6 fi are connected in parallel, the total resistance is

⦁ 54 fi

⦁ 0.3 fi

⦁ 15 fi

⦁

**3.6 fi**
34 Which of the following is a preferred resistor value?

⦁ 520

⦁

**47**
⦁ 43,000

⦁ 54,321

35 A three-by-three, series-parallel matrix of resistors, all having the same ohmic value, would have a net resistance of

⦁ One-third the value of a single resistor

⦁ Three times the value of a single resistor

⦁

**The same value as a single resistor**
⦁ Nine times the value of a single resistor

36 The electric field strength between capacitor plates has a unit of

⦁

**Volts per meter**
⦁ Volts per mil

⦁ Amperes per meter

⦁ Amperes per mil

37 For multi-plate capacitor, capacitance is proportional to

⦁

**Number of plates less one(n – 1)**
⦁ Number of plates plus one(n + 1)

⦁ Number of plates less two(n - 2)

⦁ Number of plates (n)

38 A capacitor consists of two

⦁ Conductors only

⦁ Dielectric only

⦁

**Conductors separated by a dielectric**
⦁ Dielectric separated by a conductor

39 In an ac circuit with inductive reactance, the

⦁ Phase angle of the circuit is always 45˚

⦁ Voltage across the inductance must be 90˚ out-of-phase with the applied voltage

⦁

**Current through the inductance lags its induced voltage by 90˚**
⦁ Current through the inductance and voltage across it are180˚ out-of-phase

40 If three 9 mH inductors are connected in parallel without mutual inductance then the total inductance is

⦁

**3 mH**
⦁ 9 mH

⦁ 27 mH

⦁ 18 mH

41 A series RLC circuit has a power factor at its half-power points

⦁ Unity

⦁ Leading

⦁ Lagging

⦁

**Either B or C**
42 Kirchhoff’s laws (KCL and KVL) are applicable to

⦁ DC circuits

⦁ AC circuits

⦁

**DC as well as AC circuits**
⦁ Passive networks alone

43 In calculating maximum instantaneous power voltage or current is used.

⦁

**Peak**
⦁ Average

⦁ Rms

⦁ Instantaneous

44 The area of capacitor plates increases two times, then its capacitance

⦁

**Increases two times**
⦁ Increases four times

⦁ Decreases two times

⦁ Decreases four times

45 In Norton’s theorem, the short circuit current is obtained by

⦁ Opening the load terminals

⦁

**Shorting the load terminals**
⦁ Opening the voltage source

⦁ Shorting the voltage source

46 For maximum power transfer, what is the relation between load resistance RL and internal resistance R of the voltage source?

⦁ RL = 2 r

⦁ RL = 1.5 r

⦁

**RL = r**
⦁ RL = 3 r

47 What is a rotating vector whose projection can represent either current or voltage

in an ac circuit?

⦁ Polar diagram

⦁ Scalar quantity

⦁ Velocity

⦁

**Phasor**
48 Which factor does not affect resistance?

⦁ Length

⦁ Resistivity

⦁ Cross-sectional area

⦁

**Mass**
49 Which of the following capacitors are used only in dc circuits?

⦁ Mica

⦁ Ceramic

⦁ Mylar

⦁

**Electrolytic**
50 The maximum power transfer theorem is used in

⦁ Power system

⦁

**Electronic system**
⦁ Refrigeration

⦁ Air conditioning

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