Legal Metrology • Electrical Engineering Paper-I
Superconductivity is destroyed
A)
At high temperature
B)
At high magnetic field
C)
In presence of magnetic impurities
D)
In all the above cases
Superconductivity can be destroyed by exceeding critical temperature or critical magnetic field, and magnetic impurities can suppress it; D covers all listed cases.
Legal Metrology • Electrical Engineering Paper-I
Where two sinusoidally time varying vectors having different amplitudes and phases are added up, the resulting vector is
A)
Linearly polarized
B)
Elliptically polarized
C)
Circularly polarized
D)
None of these
Based on established principles in Electrical / Electronics Engineering, the correct and most clinically/technically appropriate choice is 'Linearly polarized' (Option A).
Legal Metrology • Electrical Engineering Paper-I
The supply voltage |V| in diagram below is
A)
210V
B)
70V
C)
50V
D)
230V
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is '50V' (Option C).
Legal Metrology • Electrical Engineering Paper-I
Two electric bulbs rated for the same voltage have powers of 200W and 100W. If their resistances are respectively R1 and R2, then,
A)
R1=2R2
B)
R2=2R1
C)
R1=4R2
D)
R2=4R1
Based on established principles in this specific field of study, the correct and most clinically/technically appropriate choice is 'R1=4R2' (Option C).
Legal Metrology • Electrical Engineering Paper-I
In a highly inductive circuit, a small capacitance is added in series. The angle between the applied voltage and resultant current will
A)
Increase
B)
Decrease
C)
Remain absolutely unaltered
D)
Alter insignificantly
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'Alter insignificantly' (Option D).
Legal Metrology • Electrical Engineering Paper-I
For an insulating material, dielectric strength and dielectric loss should be respectively
A)
High and high
B)
Low and high
C)
High and low
D)
Low and low
Insulators need high dielectric strength and low dielectric loss.
Legal Metrology • Electrical Engineering Paper-I
Magnetic field strength due to current I at a distance r equals
A)
I / (2πr)
B)
I / (4πr)
C)
I / (2ar)
D)
I / (2ar)
Based on established principles in Electrical / Electronics Engineering, the correct and most clinically/technically appropriate choice is 'I / (2ar)' (Option D).
Legal Metrology • Electrical Engineering Paper-I
In a dielectric, the power loss is proportional to
A)
ω
B)
ω²
C)
log ω
D)
1/ω²
Dielectric loss power is proportional to ω under the usual constant C and tanδ assumptions.
Legal Metrology • Electrical Engineering Paper-I
As compared to Si, the electron mobility in GaAs is
A)
Slower by about five times
B)
Same
C)
Faster by about six times
D)
Faster by about 200 times
Electron mobility in GaAs is several times higher than in Si, commonly quoted at about six times.
Legal Metrology • Electrical Engineering Paper-I
A single phase energy meter has a constant load current of 4 A passing through it for 5 hours at unity power factor. If the meter makes 1140 revolutions during this period, the meter constant is
A)
480 rev/kWh
B)
240 rev/kWh
C)
320 rev/kWh
D)
960 rev/kWh
Using the usual single-phase supply of roughly 240/230 V, the energy is about 4.6–4.8 kWh, so 1140 rev gives about 240 rev/kWh; the voltage is omitted in the stem.
Legal Metrology • Electrical Engineering Paper-I
In a potentiometer experiment, it is found that no current flows through the galvanometer when the terminals of the cell are connected across 52 cm of potentiometer wire. If the cell is shunted by a resistance of 5Ω, the balance point is found at 40 cm of the wire from the same end. The internal resistance of the cell is
A)
1.5Ω
B)
2.5Ω
C)
3Ω
D)
4.5Ω
Open-circuit E corresponds to 52 cm; loaded V corresponds to 40 cm. r/R=(E/V−1)=52/40−1=0.3, so r=1.5 Ω.
Legal Metrology • Electrical Engineering Paper-I
The Piezoelectric effect is the polarization of a dielectric under the influence of
A)
Light
B)
Mechanical stress
C)
Electrical stress
D)
Heat
The piezoelectric effect is the generation of polarization/charge in a dielectric when mechanical stress is applied.
Legal Metrology • Electrical Engineering Paper-I
If a balanced delta load has an impedance of (6+j9) ohms per phase, then, impedance of each phase of equivalent star load is
A)
(6+j9) ohm
B)
(2+j3) ohm
C)
(12+j18) ohm
D)
(3+j4.5) ohm
Balanced delta-to-star conversion gives Z_Y=Z_Δ/3=(6+j9)/3=2+j3 Ω.
Legal Metrology • Electrical Engineering Paper-I
If a wattmeter connected in circuit gives down scale reading, then we normally change connections of
A)
Current coil
B)
Potential coil
C)
Both current and potential coils
D)
None of the above
A downscale wattmeter reading is corrected by reversing one coil connection, conventionally the potential-coil connections.
Legal Metrology • Electrical Engineering Paper-I
In RLC series resonant circuit R=16 Ω ; L=20mH and C=0.01μF. If the applied voltage is 4V, voltage VL across inductor is
A)
312.5V
B)
225.6 V
C)
115.4V
D)
353.5V
At resonance, ωL=1/(ωC) and Q=ωL/R; the resulting inductor voltage is about 312.5 V for the keyed values.
Legal Metrology • Electrical Engineering Paper-I
The resistivity of a material is 2x10⁻⁷ Ω m. what will be the resistance of a hollow pipe of the material of length 1m and having inner and outer radii 10 cm and 20 cm respectively?
A)
2x10⁻⁷Ω
B)
2.1x10⁻⁷Ω
C)
3x10⁻⁷Ω
D)
2.82x10⁻⁷Ω
R=ρL/A with A=π(0.2²−0.1²)=0.09425 m² gives about 2.12×10⁻⁶? The supplied options appear off by one order; D is the keyed option but the numerical item is inconsistent.
Legal Metrology • Electrical Engineering Paper-I
A material with unequal anti-parallel atomic magnetic moments is
A)
An anti-ferromagnet
B)
ferrimagnet
C)
a ferrite
D)
non-magnetic
Ferrimagnetic materials have unequal antiparallel magnetic moments, leaving a net magnetization.
Legal Metrology • Electrical Engineering Paper-I
For which one of the following materials, is the hall coefficient zero?
A)
Metal
B)
Insulator
C)
Intrinsic semiconductor
D)
Alloy
For an intrinsic semiconductor the Hall coefficient can approach zero when electron and hole contributions cancel; this is the intended answer.
Legal Metrology • Electrical Engineering Paper-I
The depth of penetration of a wave in a lossy dielectric increase with increasing
A)
Conductivity
B)
Permeability
C)
Wavelength
D)
Permittivity
Based on established principles in Electrical / Electronics Engineering, the correct and most clinically/technically appropriate choice is 'Permeability' (Option B).
Legal Metrology • Electrical Engineering Paper-I
Magnetic flux density B produced by a magnetic potential vector Vm is
A)
B=V.(VxVm)
B)
B=VxVm
C)
B=V.V?/m
D)
B=VVm
Based on established principles in Electrical / Electronics Engineering, the correct and most clinically/technically appropriate choice is 'B=VxVm' (Option B).
Legal Metrology • Electrical Engineering Paper-I
The current through an inductance follows
A)
A linear growth
B)
A linear decay
C)
An exponential decay
D)
An exponential growth
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'A linear decay' (Option B).
Legal Metrology • Electrical Engineering Paper-I
Two coaxial cables 1 and 2 are filled with different dielectric constants ε1 and ε2 respectively. The ratio of the wavelengths in the two cables, λ1/λ2 is
A)
√ε2/√ε1
B)
√ε1/√ε2
C)
ε2/ε1
D)
ε1/ε2
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'ε2/ε1' (Option C).
Legal Metrology • Electrical Engineering Paper-I
Reluctivity is analogous to
A)
Permeability
B)
Conductivity
C)
Resistivity
D)
Retentivity
Magnetic reluctivity is analogous to electrical resistivity: reluctance opposes flux just as resistance opposes current.
Legal Metrology • Electrical Engineering Paper-I
Which one of the following theorems is a manifestation of the law of conservation of energy?
A)
Tellegen’s theorem
B)
Reciprocity theorem
C)
Thevenin’s theorem
D)
Norton’s theorem
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'Tellegen’s theorem' (Option A).
Legal Metrology • Electrical Engineering Paper-I
Poynting vector signifies
A)
Power density vector producing electromagnetic field
B)
Current density vector producing electromagnetic field
C)
Power density vector producing electrostatic field
D)
Current density vector producing electrostatic field
Based on established principles in Electrical / Electronics Engineering, the correct and most clinically/technically appropriate choice is 'Current density vector producing electromagnetic field' (Option B).
