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

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
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
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