Legal Metrology • Paper-I
In the forward blocking mode of a silicon controlled rectifier, the SCR is
A)
In natural state
B)
In ON state
C)
In forward bias state
D)
In OFF state
Forward blocking means the SCR is forward biased at the anode-cathode junction but remains OFF until triggered.
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
Turn on time for an SCR is 10 μs. If an inductance is inserted in the anode circuit, the turn on time will be
A)
10 μs
B)
< 10 μs
C)
> 10 μs
D)
20 μs
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is '< 10 μs' (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
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
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
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
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
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
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
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
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
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
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
In fabrication Silicon BJT in ICs by epitaxial process, the number of diffusions used is usually
A)
9
B)
6
C)
2
D)
12
In the context of Unmapped / long tail, the most appropriate and technically accurate answer is '9' (Option A).
Legal Metrology • Paper-I
If X(z) is z/(z-a) with |z| > |a|, then what is the corresponding x(n)?
A)
e^n
B)
a^n
C)
u(n)
D)
u(n)a^n
The inverse Z-transform of z/(z−a), |z|>|a|, is a^n u(n).
Legal Metrology • Paper-I
The SI unit of resistance is
A)
Ampere
B)
Ohm-meter
C)
Coulomb
D)
Ohm
The SI unit of resistance is the ohm (Ω).
Legal Metrology • Paper-I
The temperature coefficient of a thermistor
A)
is positive
B)
is negative
C)
zero
D)
may be positive or negative depending on its composition
Thermistors generally have a negative temperature coefficient (resistance drops as temperature rises).
Legal Metrology • Paper-I
Electric flux is a field, and its density is a field.
A)
Vector, Vector
B)
Scalar, Scalar
C)
Vector, Scalar
D)
Scalar, Vector
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'Scalar, Scalar' (Option B).
Legal Metrology • Paper-I
In CMOS logic circuit the n-MOS transistor acts as:
A)
Not used in CMOS circuits
B)
Load
C)
Pull up network
D)
Pull down network
In CMOS, NMOS devices form the pull-down network.
Legal Metrology • Paper-I
What range of resistor values would you get when checking a transistor for forward- and reverse-biased conditions by an ohmmeter?
A)
100Ω to a few kΩ, exceeding 100kΩ
B)
1000Ω, exceeding 100kΩ
C)
1Ω, exceeding 100kΩ
D)
1kΩ to a few kΩ
In the context of Unmapped / long tail, the most appropriate and technically accurate answer is '1000Ω, exceeding 100kΩ' (Option B).
Legal Metrology • Paper-I
VMOS stands for:
A)
Voltage MOS
B)
Vertical MOS
C)
Variable MOS
D)
VLSIMOS
In the context of Unmapped / long tail, the most appropriate and technically accurate answer is 'Voltage MOS' (Option A).
Legal Metrology • Paper-I
The superposition theorem is applicable to
A)
Only current
B)
Only voltage
C)
Only power
D)
Current, Voltage and Power
Superposition applies only to linear functions (current and voltage), not to power which is proportional to the square.
Legal Metrology • Paper-I
A given copper of 10Ω resistance is stretched to double its original length, Its modified resistance will be
A)
5Ω
B)
7Ω
C)
20Ω
D)
40Ω
If length doubles while volume stays constant, area halves, so R=ρL/A becomes four times: 40 Ω.
