Legal Metrology • Paper-I
A source is delivering maximum power to a resistance through a network. The ratio of power delivered to the source power
A)
is always 0.5
B)
may be 0.5 or less
C)
may be 0.5 or less or more
D)
maybe 0.5 or more
At maximum power transfer, efficiency is 50%, meaning the ratio of power delivered to the load vs source is 0.5.
Legal Metrology • Paper-I
A voltage V(f) is a Gaussian ergodic random process with a mean of zero and a variance of 4 volt^2. If it is measured by a dc meter. The reading will be
A)
0
B)
2
C)
4
D)
6
A zero-mean Gaussian process has mean/DC value zero, so an ideal DC meter reads 0.
Legal Metrology • Paper-I
Should real time instruments like oscilloscopes be time invariant?
A)
Yes
B)
Sometimes
C)
Never
D)
They have no relation with time variance
An ideal measuring instrument should be time-invariant so its characteristics do not change with time.
Legal Metrology • Paper-I
The analog signal m(t) is given below m(t) = 4 cos 100 πt + 8 sin 200 πt + cos 300 πt, the Nyquist sampling rate will be
A)
1/100
B)
1/200
C)
1/300
D)
1/600
The highest message frequency is 150 Hz because 300π rad/s =150 Hz, so the Nyquist rate is 300 Hz.
Legal Metrology • Paper-I
In a transistor
A)
I_E = I_B
B)
I_C = I_B
C)
I_E = I_C - I_B
D)
I_E = I_C + I_B
In the context of Unmapped / long tail, the most appropriate and technically accurate answer is 'I_E = I_C + I_B' (Option D).
Legal Metrology • Paper-I
An SCR is turned off by
A)
Reducing anode voltage to zero
B)
Reverse bias the gate
C)
Removing gate signal
D)
Forward bias condition
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'Forward bias condition' (Option D).
Legal Metrology • Paper-I
An electrolytic capacitor can be used for
A)
AC and DC
B)
AC only
C)
DC only
D)
None of these
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'AC only' (Option B).
Legal Metrology • Paper-I
A voltage wave having 5% fifth harmonic content is applied to a series RC circuit. The percentage fifth harmonic content in the current wave will be
A)
5%
B)
more than 5%
C)
less than 5%
D)
equal or more than 5%
In a series RC circuit, capacitive reactance decreases with frequency, so higher harmonics produce proportionally larger currents; fifth-harmonic percentage increases above 5%.
Legal Metrology • Paper-I
Find the Z-transform of δ(n+3)
A)
z^3
B)
z^-3
C)
z
D)
z^-1
Z{δ(n+3)}=z³ under the standard bilateral Z-transform definition.
Legal Metrology • Paper-I
Air capacitors are generally available in the range
A)
10 to 400 pF
B)
100 to 120 pF
C)
400 to 700 pF
D)
5 to 100 pF
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is '5 to 100 pF' (Option D).
Legal Metrology • Paper-I
Which of the following gives piezo-electric effect?
A)
Mumetal
B)
PVDF
C)
Sapphire
D)
Ferrites
In the context of Mechanical Engineering, the most appropriate and technically accurate answer is 'Ferrites' (Option D).
Legal Metrology • Paper-I
The intrinsic concentration in a semiconductor at 300°K is 10^10 cm-3. When it is doped with donor type impurities, the majority carrier concentration becomes 10^17 cm-3. What is the value of its minority carrier density?
A)
3 x 10^3 cm-3
B)
10^3 cm-3
C)
10^2 cm-3
D)
10^0 cm-3
Based on established principles in Electrical / Electronics Engineering, the correct and most clinically/technically appropriate choice is '10^3 cm-3' (Option B).
Legal Metrology • Paper-I
The maximum number of electrons in each shell of an atom is
A)
7
B)
2n^2 where n is the number of the shell
C)
9
D)
2
Maximum electrons in shell n is 2n².
Legal Metrology • Paper-I
Consider a DC voltage source connected to a series R-C circuit. When the steady state reaches, the ratio of the energy stored in the capacitor to the total energy supplied by the voltage source, is equal to
A)
0.5
B)
0.73
C)
1.52
D)
7.7
A DC source supplies QV energy, while the capacitor stores 1/2 QV. The ratio is 0.5.
Legal Metrology • Paper-I
If transfer function of a system is H(z) = 6 + z^-1 + z^-2 then system is
A)
minimum phase
B)
maximum phase
C)
mixed phase
D)
mixed and minimum phases
The zeros of 6z²+z+1 lie inside the unit circle, so the causal system is minimum-phase.
Legal Metrology • Paper-I
A silicon controlled rectifier is turned on if the anode current is greater than
A)
Trigger current
B)
Anode current
C)
Cathode current
D)
Holding current
An SCR is latched ON when anode current rises above its latching/holding threshold; among the choices, holding current is the relevant threshold.
Legal Metrology • Paper-I
If three 15 uF capacitors are connected in series, the net capacitance is,
A)
15 uF
B)
25 uF
C)
35 uF
D)
5 uF
Based on established principles in Electrical / Electronics Engineering, the correct and most clinically/technically appropriate choice is '35 uF' (Option C).
Legal Metrology • Paper-I
As the Fermi energy of silver is 8.8 x 10^-19 Joule, the velocity of the fastest electron in silver at 0°K (Given: Rest mass of electron = 9.1 x 10^-31 kg) is
A)
7 x 10^6 m/s
B)
7.22 x 10^6 m/s
C)
1.39 x 10^6 m/s
D)
1.97 x 10^7 m/s
In the context of Mechanical Engineering, the most appropriate and technically accurate answer is '1.39 x 10^6 m/s' (Option C).
Legal Metrology • Paper-I
Effective Q of the equivalent electrical circuit of a quartz crystal is of the order of
A)
2,00,000
B)
3,00,000
C)
4,00,000
D)
5,00,000
Quartz crystals are highly stable and have an exceptionally high Q factor, typically in the range of 2,00,000.
Legal Metrology • Paper-I
The Superposition theorem requires as many circuits to be solved as there are
A)
Sources
B)
Nodes
C)
Sources and nodes
D)
Sources, nodes and meshes
Superposition requires evaluating the circuit for each independent source separately.
Legal Metrology • Paper-I
In the active region of a transistor, collector-base junction is biased.
A)
Forward, forward
B)
Reverse, reverse
C)
Reverse, forward
D)
Forward, reverse
In the context of Unmapped / long tail, the most appropriate and technically accurate answer is 'Forward, forward' (Option A).
Legal Metrology • Paper-I
The type of systems which are characterized by input and the output capable of taking any value in a particular set of values are called as,
A)
discrete
B)
digital
C)
analog
D)
continuous
Analog/continuous systems can take any value in a continuous set; digital systems are discrete.
Legal Metrology • Paper-I
The longest wavelength that can be absorbed by silicon, which has the bandgap of 1.12 eV is 1.1 μm. If the longest wavelength that can be absorbed by another material is 0.87 μm, then the bandgap of this material is
A)
0.99 eV
B)
1.42 eV
C)
1.1 eV
D)
2.3 eV
Based on established principles in Electrical / Electronics Engineering, the correct and most clinically/technically appropriate choice is '2.3 eV' (Option D).
Legal Metrology • Paper-I
Fourier transform of a signal h(t) is H(jω) = (2cos ω)(sin 2ω) / ω. The value of h(0) is
A)
1
B)
1/2
C)
1/4
D)
1/8
h(0)=(1/2π)∫H(jω)dω; using ∫sin(aω)/ω dω=π gives h(0)=1.
Legal Metrology • Paper-I
In an n-type silicon crystal at room temperature, which of the following can have a concentration of 4 x 10^19 /cm3?
A)
Silicon atoms
B)
Holes
C)
Dopant atoms
D)
Valence electrons
Based on established principles in Electrical / Electronics Engineering, the correct and most clinically/technically appropriate choice is 'Silicon atoms' (Option A).
