ELECTRICAL CIRCUITS Multiple Choice Questions Part 5.

1 For series 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

2 A wire of one kilometre length has a resistance of 20 fi. If the length is halved, then the new resistance is the original resistance.

⦁

**Half**

⦁ Twice

⦁ One-fourth

⦁ Three times

3 What is the total resistance of a two equal valued resistors in series?

⦁ The difference of both

⦁ The product of both

⦁

**Twice as one**
⦁ The sum of their reciprocals

4 The ratio of maximum value to the effective value of an alternating quantity is called

⦁ Form factor

⦁

**Peak factor**
⦁ Dynamic factor

⦁ Leakage factor

5 The reason why alternating current can induce voltage is

⦁ It has high peak value

⦁ It has a stronger magnetic field than direct current

⦁ It has a constant magnetic field

⦁

**It has a varying magnetic field**
6 When two unequal values of resistors are connected in parallel across a dc source,

greater current flows through the

⦁ Higher resistance

⦁

**Lower resistance**
⦁ Higher wattage resistance

⦁ Lower wattage resistance

7 Which of the following is a way of decreasing mutual inductance?

⦁ Moving the coils closer

⦁

**Moving the coils apart**
⦁ Decreasing the number of turns of either coil

⦁ Increasing the number of turns of either coil

8 The charging of a capacitor through a resistance obeys

⦁

**Exponential law**
⦁ Logarithmic law

⦁ Linear law

⦁ Square law

9 A capacitance of 0.05 µF equals.

⦁ 0.05 x 106 F

⦁

**0.05 x 10-6 F**
⦁ 0.05 x 10-12 F

⦁ 0.05 x 1012 F

10 The factor 0.707 for converting peak to rms applies only to

⦁ Square waves

⦁ Triangle waves

⦁ Sawtooth waves

⦁

**Sine waves**
11 When two in-phase sine waves that have identical frequency and amplitude are added together, then the result is a sine wave with the amplitude of either.

⦁ Half

⦁

**Twice**
⦁ Four times

⦁ One-fourth

12 Tungsten filament of bulbs has a hot resistance higher than its cold resistance due to its temperature coefficient which is

⦁

**Positive**
⦁ Negative

⦁ Zero

⦁ Infinite

13 A term used to express the amount of electrical energy stored in electrostatic field.

⦁

**Joules**
⦁ Coulombs

⦁ Watts

⦁ Electron-volt

14 Which of the following capacitors is suitable for dc filter circuits?

⦁ Mica

⦁ Ceramic

⦁ Paper

⦁

**Electrolytic**
15 A series RL circuit has R of 10 fi and XL of 5 fi, its impedance in rectangular

form is given by

⦁

**10 + j 5 fi**
⦁ 10 + j 10 fi

⦁ 10 – j 5 fi

⦁ 10 – j 10 fi

16 When frequency of an ac wave decreases, the value of XL in a coil

⦁

**Approaches zero**
⦁ Gets larger positively

⦁ Gets larger negatively

⦁ Stays constant

17 What is the reciprocal of capacitance?

⦁ Reluctance

⦁ Susceptance

⦁

**Elastance**
⦁ Conductance

18 The resistance of an insulator when its temperature is increased.

⦁

**Decreases**
⦁ Remains the same

⦁ Increases

⦁ Varies

19 The wavelength of an alternating waveform depends upon the of the variation.

⦁ Period

⦁ Number

⦁

**Frequency**
⦁ Amplitude

20 In a complex number 5 + j 10, 10 is called part.

⦁

**Imaginary**
⦁ Real

⦁ Conjugate

⦁ Integer

21 The presence of an electric current is made known by

⦁ Electric shock

⦁

**Effects produced**
⦁ Magnetic shock

⦁ Flashing

22 The reciprocal of a complex number is

⦁

**A complex number**
⦁ A real number

⦁ An imaginary number

⦁ A whole number

23 Which of the following has negative temperature coefficient?

⦁

**Carbon**
⦁ Nickel

⦁ Brass

⦁ Constantan

24 In dividing or multiplying phasor quantities_____form is used.

⦁

**Polar**
⦁ Rectangular

⦁ Trigonometric

⦁ Exponential

25 The capacitance of a capacitor is relative permittivity.

⦁

**Directly proportional to**
⦁ Inversely proportional to

⦁ Equal to

⦁ Inversely proportional to the square of

26 If a multiplate capacitor has 10 plates, each of area 10 cm2, then

⦁ 10 capacitors will be in parallel

⦁ 10 capacitors will be in series

⦁

**9 capacitors will be in parallel**
⦁ 9 capacitors will be in series

27 A neon glow lamp used as a night light ionizes at approximately

⦁

**70 V**
⦁ 80 V

⦁ 90 V

⦁ 100 V

28 What dielectric is generally employed by a variable capacitor?

⦁ Mica

⦁

**Air**
⦁ Electrolyte

⦁ Ceramic

29 If the inductance is decreased, the impedance of the circuit containing a resistor a

capacitor and an inductor connected in series to an ac source

⦁ Decreases

⦁ Increases

⦁

**Decreases or increases**
⦁ Decreases, increases or remains the same

30 When the movable plates of a gang capacitor completely overlap the fixed plates, the capacitance of the capacitor is

⦁ Halfway between maximum and minimum

⦁

**Maximum**
⦁ Minimum

⦁ Zero

31 When the temperature of copper wire is increased its resistance is

⦁

**Increased**
⦁ Decreased

⦁ Constant

⦁ Zero

32 A trimmer is a variable capacitor in which capacitance is varied by changing the

⦁ Number of plates

⦁ Dielectric

⦁

**Distance between plates**
⦁ Plate area

33 When current and voltage arte in phase in an ac circuit, the is equal to zero.

⦁ Resistance

⦁

**Reactance**
⦁ Inductance

⦁ Capacitance

34 Thevenin’s theorem is what form of an equivalent circuit?

⦁ Current

⦁

**Voltage**
⦁ Both current and voltage

⦁ Neither current nor voltage

35 When resistance are connected in parallel, the total resistance is

⦁

**Less than the smallest resistance in the connection**
⦁ Greater than the smallest resistance in the connection

⦁ Between the smallest and greatest resistance in the connection

⦁ Increasing and decreasing depending upon the supply voltage

36 The arc across a switch when it open an RL circuit is a result of the

⦁

**Large self-induced voltage across L**
⦁ Long time constant

⦁ Low resistance of the open switch

⦁ Surge of resistance

37 In an ac circuit with a resistive branch and an inductive branch in parallel, the

⦁ Voltage across the inductance leads the voltage across the resistance by 90°

⦁

**Resistive branch current is 90° out of phase with the inductive branch current**
⦁ Resistive and inductive branch currents have the same phase

⦁ Resistive and inductive branch currents are 180° out-of-phase

38 Voltage resonance means

⦁

**Series resonance**
⦁ Parallel resonance

⦁ Current magnification

⦁ Gain magnification

39 Which of the following is not a factor affecting dielectric strength?

⦁

**Mass**
⦁ Moisture content

⦁ Temperature

⦁ Thickness

40 A factor that states how much the resistance changes for a change in temperature?

⦁ Resistivity

⦁ Specific resistance

⦁ Coefficient of temperature change

⦁

**Temperature coefficient of resistance**
41 An alloy composed of 84 % copper, 12 % manganese and 4 % nickel.

⦁

**Manganin**
⦁ Constantan

⦁ Nichrome

⦁ German silver wire

42 In a rectangular wave, the peak factor is.

⦁ 1.16

⦁ 1.73

⦁ 1.11

⦁

**1.0**
43 The ohmic value of a resistor with negative temperature coefficient

⦁ Increases with increasing temperature

⦁

**Increase with decreasing temperature**
⦁ Stays unchanged with temperature change

⦁ Stays unaffected even with increasing temperature

44 What is the form factor of a triangular wave?

⦁

**1.16**
⦁ 1.11

⦁ 1.73

⦁ 1.41

45 In a multiple capacitor, the plate area is

⦁

**Increased**
⦁ The same

⦁ Decreased

⦁ Variable

46 What is the time constant for L of 240 mH in series with R of 20 fi?

⦁

**12 ms**
⦁ 4.8 s

⦁ 83.3 s

⦁ 12 s

47 In an ac circuit, the power dissipated as heat depends on

⦁ Impedance

⦁ Capacitive reactance

⦁

**Resistance**
⦁ Inductive reactance

48 The power factor of a circuit is equal to

⦁ RZ

⦁ XC/Z

⦁ XL/Z

⦁

**R/Z**

49 What fusion of elements is without chemical action between them?

⦁ Mixture

⦁ Compound

⦁

**Alloy**
⦁ Ionization

50 In a circuit, a passive element is one which

⦁ Supplies energy

⦁

**Receives energy**
⦁ Both supplies and receives energy

⦁ Attenuates signal

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