ELECTRICAL CIRCUITS Multiple Choice Questions Part 4.

1 In a series RLC circuit

⦁ Increasing the frequency decreases the resistance

⦁ Increasing the frequency increases the resistance

⦁

**Both XL and XC change as frequency changes**

⦁ Impedance will always decrease

2 The average value of a triangular or sawtooth wave is times its peak value.

⦁

**0.577**

⦁ 0.500

⦁ 0.318

⦁ 0.637

3 A series RLC circuit consists of a 10 fi resistor in series with L = 10 µH, and C = 100 µF. Determine a new value of I, for which the resonant frequency is one –half the original value.

⦁

**40 µH**

⦁ 40 mH

⦁ 40 pH

⦁ 40 nH

4 The impedance in the study of electronics is represented by resistance and

⦁ Inductance

⦁ Capacitance

⦁ Inductance and capacitance

⦁

**Reactance**
5 Loop currents should be assumed to flow in which direction

⦁ Straight

⦁ Clockwise

⦁ Counter-clockwise

⦁

**Either B or C arbitrarily selected**
6 What determines the direction of induced emf in a conductor or coil?

⦁ Cork screw rule

⦁ Fleming’s left hand rule

⦁ Ampere’s circuital law

⦁

**Fleming’s right hand rule**
7 The superposition theorem is used when the circuit contains

⦁ Reactive elements

⦁ Active elements

⦁

**Number of voltage sources**
⦁ Single voltage source

8 What refers to such work at very low temperatures, near absolute zero?

⦁

**Cryogenics**
⦁ Superconductivity

⦁ Subsonic

⦁ Thermionic

9 Which of the statements below is not true?

⦁ Current source is an active element

⦁ Resistor is a linear element

⦁

**Voltage source is a passive element**
⦁ Diode is a non-linear element

10 The potential gradient in a cable is maximum in

⦁

**Conductor**
⦁ Outer sheath

⦁ Insulation

⦁ Uniformly all over

11 Which statement is true about a passive circuit?

⦁

**A circuit with neither a source of current nor a source of potential difference**
⦁ A circuit with a voltage source

⦁ A circuit with a current source

⦁ A circuit with only resistance as a load

12 What is the conductance of a circuit having three 10 fi resistors in parallel?

⦁

**0.3 S**
⦁ 3.33 S

⦁ 0.33 S

⦁ 30 S

13 If an emf in circuit A produces a current in circuit B, then the same emf in circuit

B produces the same current in circuit A. this theorem is known as

⦁ Maximum power transfer theorem

⦁ Millman’s theorem

⦁ Reciprocity theorem

⦁

**Norton’s theorem**
14 According to Gauss theorem, flux can be equated to

⦁

**Charge**
⦁ Field intensity

⦁ Current

⦁ Voltage

15 An open resistor when checked with an ohmmeter reads

⦁ Zero

⦁

**Infinite**
⦁ High but within the tolerance

⦁ Low but not zero

16 For parallel capacitors, total charge is

⦁

**The sum of individual charges**
⦁ Equal to the charge of either capacitors

⦁ Equal to the product of the charges

⦁ The quotient of the charges

17 In a complex resistance-reactance plane, XL is represented

⦁ By an axis opposite the R axis

⦁ By an axis perpendicular to the XC axis

⦁

**By an axis opposite the XC axis**
⦁ By an axis parallel to the R axis

18 When the net reactance in a series coil-capacitor circuit is zero at frequency f, the nature of its reactance of frequency 2f is

⦁

**Inductive**
⦁ Capacitive

⦁ Resistive

⦁ Infinite

19 Refers specifically to steady state values of quantities in ac circuits which are

complex numbers.

⦁ Domain

⦁ Scalar quantity

⦁ Vector quantity

⦁

**Phasor quantity**
20 A capacitor is used to

⦁

**Block dc current**
⦁ Pass dc current

⦁ Open voltage source

⦁ Short the voltage source

21 The usual load of a dc circuit is a/an

⦁

**Resistor**
⦁ Capacitor

⦁ Inductor

⦁ Both inductor and capacitor

22 What is the value of a carbon composition resistor with the following color code:

Brown, white, orange, red.

**190 fi; 10 %**

⦁ 19 kfi; 2 %

⦁ 19 kfi; 20 %

⦁ 1.9 kfi; 2 %

23 How many coulombs are delivered by a storage battery in 25 hours if it is supplying current at the rate of 3 A?

⦁ 2.592 x 105 C

⦁

**2.592 x 103 C**
⦁ 2.592 x 108 C

⦁ 2.592 x 1012 C

24 The temperature-resistance coefficient of pure gold is

A.

**0.0034**
B. 0.0037

C. 0.0038

D. 0.0039

25 The capacitor opposes any change in voltage across it by

⦁ Passing a voltage proportional to the rate of change of current

⦁ Acting as a short circuit at time equal to zero

⦁

**Passing a current proportional to the rate of change of voltage**
⦁ Acting as a short circuit at time equal to infinity

26 What is the most common non-sinusoidal waveform?

⦁

**Square wave**
⦁ Triangular wave

⦁ Trapezoidal wave

⦁ Sawtooth wave

27 What is the peak factor of a triangular wave?

⦁

**1.16**
⦁ 1.73

⦁ 1.41

⦁ 1.11

28 Effects of capacitance

⦁ It opposes any change in the amount of voltage

⦁ Voltage is lagged behind the current by a quarter cycle

⦁ Electric energy is stored in the capacitor in the form of electrostatic field

⦁

**All of the above**
29 The reason why electrical appliances are connected in parallel.

⦁ It is a simple circuit

⦁

**This makes the operation of appliances independent with each other**
⦁ This results in reduced power consumption

⦁ All of the above

30 A capacitor is basically constructed of

⦁

**Two conductors separated by a dielectric**
⦁ Two dielectric separated by a conductor

⦁ Conductors and dielectric

⦁ Conductors and semiconductors

31 In an inductive coil, the rate of rise of current is maximum

⦁

**Near the final maximum value of current**
⦁ At mid-value of current

⦁ At half-power points

⦁ After one time constant

32 Two complex numbers or phasors are said to be conjugate if they

⦁

**Differ only in the algebraic sign of their quadratic components**
⦁ Differ only in the algebraic sign of their real components

⦁ Are equal in their real and quadrature components including algebraic signs

⦁ Are equal in their real components but differ in their quadrature components including algebraic signs.

33 Which of the following dielectric materials makes the highest-capacitance

capacitor?

⦁ Air

⦁

**Barium-strontium titanite**
⦁ Mica

⦁ Electrolyte

34 In a circuit, an active element is one which

⦁

**Supplies energy**
⦁ Receives energy

⦁ Both supplies and receives energy

⦁ Amplifies signal

35 The of an alternating quantity is defined as the fractional part of a period or

cycle through which the quantity has advanced from selected origin.

⦁

**Phase**
⦁ Frequency

⦁ Amplitude

⦁ Waveform

36 An inductive circuit of resistance 16.5 fi and inductance of 0.14 H takes a current

of 25 A. if the frequency is 50 Hz, find the supply voltage.

⦁ 1501 V

⦁

**1174 V**
⦁ 1877 V

⦁ 991 V

37 What is the total effective capacitance of two 0.25 µF capacitors connected in series?

⦁

**0.125 µF**
⦁ 1.25 µF

⦁ 0.50 µF

⦁ 2.5 if

38 What can be used to estimate resonant frequency and to find reactance at any frequency for any value of capacitor or inductor?

⦁ Smith chart

⦁

**Reactance chart**
⦁ Impedance chart

⦁ Resonance chart

39 For a parallel AC circuit, is used as a reference phasor.

⦁

**Voltage**
⦁ Power

⦁ Current

⦁ Resistance

40 A 0.09 microfarad capacitor is charged to 220 volts. How long in milliseconds will it discharged resistor has a resistance of 20,000 ohms?

⦁ 1.5

⦁ 2.5

⦁

**1.25**
⦁ 0.5

41 “Any resistance R in a branch of a network in which a current I is flowing can be replaced by a voltage equal to IR”. This states

⦁

**Compensation theorem**
⦁ Reciprocity theorem

⦁ Millman’s theorem

⦁ Superposition theorem

42 The internal resistance of an ideal current source is

⦁

**Infinite**
⦁ Zero

⦁ Equal to the load resistance

⦁ To be determined

43 Series resonant circuit is sometimes known as

⦁ Rejector circuit

⦁

**Acceptor circuit**
⦁ Inductive circuit

⦁ Capacitive circuit

44 Parallel resonant circuit is sometimes called as

⦁ Acceptor circuit

⦁

**Rejector circuit**
⦁ Inductive circuit

⦁ Capacitive circuit

45 When two pure sine waves of the same frequency and the same amplitude which are exactly 180˚ out-of-phase are added together, the result is

⦁ A wave with twice the amplitude

⦁ A wave with half the amplitude

⦁

**Zero signal**
⦁ A wave with twice the frequency

46 If two complex conjugates are added, components results.

⦁

**In-phase**
⦁ Quadrature

⦁ Complex

⦁ Out-of-phase

47 Norton’s theorem is Thevenin’s theorem.

⦁ The same as

⦁

**The converse of**
⦁ Older that

⦁ More accurate than

48 The admittance of a parallel RLC circuit is found to be the sum of conductance and susceptances.

⦁ Algebraic

⦁ Arithmetic

⦁ Vector

⦁

**Phasor**
49 Which of the following has a positive temperature coefficient?

⦁ Mica

⦁

**Manganin**
⦁ Silicon

⦁ Carbon

50 The ratio of the flux density to the electric field intensity in the dielectric is called

⦁

**Permittivity**
⦁ Field intensity

⦁ Permeability

⦁ Elasticity

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