ELECTRICAL CIRCUITS Multiple Choice Questions Part 6.

1 In a rectangular wave, the form factor is.

⦁ 1.11

⦁ 1.16

⦁

**1.0**

⦁ 1.73

2 Electric energy refers to

⦁ Volt divided by coulomb

⦁ Volt-ampere

⦁

**Volt-coulomb**

⦁ Watt divided by time

3 A capacitor requires 12 µC of charge to raise its potential of 3 V. What is the capacitance of the capacitor?

⦁ 36 µF

⦁ 15 µF

⦁ 0.25 µF

⦁

**4 µF**
4 A capacitor opposes change in

⦁

**Voltage**
⦁ Current

⦁ Voltage and current

⦁ Neither voltage nor current

5 A series-parallel combination of identical resistors will

⦁

**Increase the power rating compared with one resistor alone**
⦁ Increase the voltage rating compared with one resistor alone

⦁ Reduce the voltage rating compared with resistor alone

⦁ Result in an expensive circuit

6 It is impossible to change the voltage across a capacitor instantly, as this would produce current.

⦁

**Infinite**
⦁ Zero

⦁ Low

⦁ High

7 Which of the following is not a factor affecting capacitance of a basic capacitor?

⦁ Area of plates

⦁

**Number of plates**
⦁ Distance between plates

⦁ Dielectric material used

8 When voltage is applied across a ceramic dielectric the electrostatic field produced is 50 times greater than air dielectric. The dielectric constant of ceramic therefore is

⦁

**50**
⦁ 100

⦁ 16.67

⦁ 5

9 High resistance values are a consequence of the of the film.

⦁ Thickness

⦁ Length

⦁

**Thinness**
⦁ Area

10 A 5 µF capacitor charge to 5V has a stored charge equal to

⦁ 1 µc

⦁ 5 µc

⦁

**25 µC**
⦁ 200 µc

11 Liquids that are good conductors because of ionization are called

⦁ Electrolytic

⦁ Bases

⦁ Acid

⦁

**Electrolytes**
12 With double the number of turns by the same length and area, the inductance is

⦁ The same

⦁ Doubled

⦁ Quartered

⦁

**Quadrupled**
13 The temperature coefficient of resistance of electrolytes is

⦁

**Negative**
⦁ Positive

⦁ Zero

⦁ Infinite

14 What refers to the lowest voltage across any insulator that can cause current flow?

⦁ Conduction voltage

⦁ Critical voltage

⦁

**Breakdown voltage**
⦁ Voltage capacity

15 The second strip of an electronic resistor color-code represents

⦁ The multiplier

⦁

**The second digit of the value**
⦁ The temperature

⦁ The tolerance

16 If the output resistance of a voltage source is 4 fi, it internal resistance should be

⦁

**4 fi**
⦁ 8 fi

⦁ 2 fi

⦁ Infinite

17 The curve between current and frequency is termed as

⦁ Voltage curve

⦁ Gain curve

⦁ Power curve

⦁

**Resonance curve**
18 For a series AC circuit, is not used as a reference phasor.

⦁

**Voltage**
⦁ Impedance

⦁ Current

⦁ Conductance

19 If a certain circuit has a current that is lagging the voltage by 45˚, then it displays

⦁ Pure inductive reactance

⦁ Resistance and capacitance reactance

⦁

**Resistance and inductive reactance**
⦁ Pure capacitive reactance

20 Which of the following materials has the lowest dielectric strength?

⦁ Glass

⦁

**Paper**
⦁ Mica

⦁ Teflon

21 The distance between the capacitor plates increases two times, then its capacitance

⦁ Increases two times

⦁ Increases four times

⦁

**Decreases two times**
⦁ Decreases four times

22 The ratio between the active power and the apparent power of a load in an ac circuit is called

⦁ Quality factor

⦁

**Power factor**
⦁ Power ratio

⦁ Power reactive

23 The power factor of a certain circuit in which the voltage lags behind the current is 80 %. To increase the power to 100 %, it is necessary to add to the circuit.

⦁

**Inductance**
⦁ Capacitance

⦁ Resistance

⦁ Impedance

24 Refers to the outward-curving distortion of the lines of force near the edges of two parallel metal plates that form a capacitor.

⦁ Skin effect

⦁ Night effect

⦁

**Edge effect**
⦁ Hall effect

25 If voltage across the plates of 2 F capacitor is increased by 4 V, then charge on the plates will

⦁ Decrease by 2 C

⦁ Increase by 2 C

⦁ Decrease by 4 C

⦁

**Increase by 4 C**
26 What does a capacitor store?

⦁ Voltage

⦁

**Charge**
⦁ Current

⦁ Power

27 For greater accuracy, the value of phase angle 0 should be determined from

⦁ Cos 0

⦁

**Tan 0**
⦁ Sin 0

⦁ Sec 0

28 Inductive reactance applies only to sine waves because it

⦁ Increases with lower frequencies

⦁ Increases with lower inductance

⦁

**Depends on the factor 2 v**
⦁ Decreases with higher frequencies

29 What increases the resistance of wire at high frequencies?

⦁ Temperature

⦁ Voltage

⦁

**Skin effect**
⦁ Insulation

30 In the 5-band method of capacitor color coding, the first band indicates

⦁

**Temperature coefficient**
⦁ Tolerance

⦁ 1st digit

⦁ Capacitance value

31 What is the most convenient way of achieving large capacitance?

⦁

**By using multiplate construction**
⦁ By using air as dielectric

⦁ By decreasing distance between plates

⦁ By using dielectric of low permittivity

32 A linear circuit is one whose parameters

⦁ Change with change in voltage

⦁ Change with change in current

⦁

**Do not change with voltage and current**
⦁ Change with change in voltage and current

33 For a linear circuit, voltage or current is used to calculate average power.

⦁

**Rms**
⦁ Peak

⦁ Average

⦁ Instantaneous

34 For a carbon composition resistor, typical resistance values range from

⦁

**2.7 fi to 22 Mfi**
⦁ 1000 fi to 10000 fi

⦁ 10 fi to 10 Mfi

⦁ 2.7 fi to 2.7 Gfi

35 The rms value of a triangular or sawtooth waveform is times its peak value.

⦁

**0.577**
⦁ 0.500

⦁ 0.25

⦁ 0.707

36 Rationalizing the denominator of a complex number means

⦁

**Eliminating the j component in the denominator**
⦁ Adding j component in the denominator

⦁ Eliminating the j component in the numerator

⦁ Adding j component in the numerator

37 When two complex conjugates are subtracted, the result is a

⦁

**Quadrature component only**
⦁ Complex component

⦁ In-phase component

⦁ Real component

38 A coil of inductance L has an inductive reactance of XL in an ac circuit in which the effective current is I. The coil is made from a superconducting material. The rate at which power is dissipated in the coil is

⦁

**0**
⦁ I2XL

⦁ IXL

⦁ L

⦁ IX 2

39 The reason why electrical appliances are not connected in series.

⦁ Greater electrical power saving

⦁ Power loss is minimum

⦁

**Appliances have different current ratings**
⦁ All of the above

40 Form its definition, the unit of electric field, £ is the N/C and equivalent unit of £

is the

⦁ V(m)2

⦁ V(m)

⦁ V/m2

⦁

**V/m**
41 Which of the following combination of length and cross-sectional area will give a

certain volume of copper the least resistance?

⦁ 2L and1/2 A

⦁ Does not matter because the volume of copper remains the same

⦁ L and A

⦁

**½ L and 2 A**
42 Norton’s theorem is what form of an ac equivalent circuit?

⦁ Voltage

⦁

**Current**
⦁ Both voltage and current

⦁ Neither voltage nor current

43 What is the total capacitance of 10 capacitors, each of 20 µF in series?

⦁ 200 µF

⦁

**2 µF**
⦁ 100 µF

⦁ 0.5 µF

44 If the capacitance of mica capacitor is 5 times the capacitance of air capacitor, then the relative permittivity of mica is

⦁ 2.5

⦁

**5**
⦁ 10

⦁ 25

45 The hot resistance of an incandescent lamp is about times its cold resistance.

⦁

**10**
⦁ 5

⦁ 50

⦁ 100

46 An inductive load always has a power factor

⦁ Leading

⦁

**Lagging**
⦁ Zero

⦁ Unity

47 Of the equivalent combination of units, which one is not equal to watt?

⦁

**fi2/V**
⦁ AV

⦁ A2fi

⦁ J/s

48 Which of the following is a disadvantage of a wire-wound resistor?

⦁

**It has reactance in radio-frequency circuits**
⦁ It cannot handle much power

⦁ It draws a large amount of current

⦁ It cannot handle high voltage

49 Delta to wye or wye to delta transformation technique is applied to a network.

⦁ One-terminal

⦁ Two-terminal

⦁

**Three-terminal**
⦁ Complex

50 In an ac wave, 30 degrees of phase is of a cycle.

⦁ ½

⦁

**1/12**
⦁ 1/3

⦁ 1/30

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