← MES Jr. Grade
Past Questions
The most widely used tube well in India is
A)
Strainer well
B)
Cavity well
C)
Slotted well
D)
Perforated well
The most widely used tube well in India is the strainer well. It is suitable for aquifers with sand and gravel and is commonly adopted because it is effective and economical. Cavity wells are used only in certain hard strata conditions, while slotted and perforated wells are less common as standard tube well types.
The difference between the total rainfall and that which is intercepted is called
A)
Rainfall interception
B)
Residual rain
C)
Net rainfall
D)
Ground rainfall
Interception is the portion of rainfall caught by vegetation, roofs, etc., and does not reach the ground. The rainfall remaining after subtracting interception from total rainfall is called net rainfall.
So:
- Total rainfall - intercepted rainfall = net rainfall
- Option (a) is the process itself, not the remainder.
- Option (b) is not the standard hydrology term here.
- Option (d) ground rainfall is not the accepted term for this definition.
Intensity of rainfall is
A)
Total rainfall ina period
B)
Rainfall per unit area
C)
Volume of water collected per unit time
D)
Depth of rainfall per unit time during which it fell
Rainfall intensity is defined as the rate of rainfall, i.e., the depth of rain falling in a given unit time, usually expressed in mm/h. Option (d) matches this definition exactly. Option (a) is total rainfall over a period, not intensity. Option (b) refers to rainfall amount over an area, and option (c) is not the standard definition of rainfall intensity.
Cross regulators in main canals are provided
A)
To regulate water supply in the distributaries
B)
To increase water head upstream when a main canal is running with low supply
C)
To overflow excessive flood water
D)
None of these
A cross regulator is constructed across a main canal to control the water level in the canal. When the canal is carrying a low supply, it helps raise and maintain the upstream water head so that water can still be diverted into off-taking channels and distributaries. Option (a) is the function of distributary head regulators, not cross regulators. Option (c) describes a spillway or waste weir, not a cross regulator.
The intensity-duration-frequency curves for precipitation indicate
A)
that the greater the intensity of rainfall the shorter length of time it continues
B)
the days on which rainfall occurs at a location
C)
that cumulative rainfall over a period with frequency of periodic peaks is ultimately constant
D)
thatthe intensity of rainfall increases as the duration increases
Intensity-duration-frequency (IDF) curves show the relationship among rainfall intensity, storm duration, and return period. In general, for a given frequency, shorter-duration storms have higher rainfall intensity, while longer-duration storms have lower intensity. Therefore, the correct statement is that the greater the intensity of rainfall, the shorter the length of time it continues. Option (d) is the opposite of this relationship, and (b) and (c) do not describe IDF curves.
Which of the following is the standard treatment of rapid sand filter plants?
A)
Plain chlorination
B)
Pre chlorination
C)
Post chlorination
D)
Super chlorination
Rapid sand filters are commonly preceded by chlorination to control algae, reduce taste and odor, and aid coagulation and filtration performance. This is called pre-chlorination. Plain chlorination is not a specific treatment stage, post-chlorination is done after filtration and disinfection, and super-chlorination is an excessive dose used only in special conditions, not as the standard treatment of rapid sand filter plants.
The minimum diameter of an opening of a manhole should be
A)
50cm
B)
100cm
C)
25cm
D)
150 cm
A manhole opening must be large enough for a person to enter, inspect, and maintain the sewer safely. The standard minimum diameter of a manhole opening is 100 cm (1 m). Smaller options like 25 cm or 50 cm are too small for human access, while 150 cm is larger than the minimum requirement.
Raw water treated with only chlorine is known as :
A)
Plain chlorination
B)
First chlorination
C)
Pre-chlorination
D)
De-chlorination
Raw water that is treated with chlorine before any other treatment steps is called pre-chlorination. It is commonly done at the intake or before sedimentation to control algae, reduce taste and odor, and help in purification.
Why others are incorrect:
- Plain chlorination: not the standard term for chlorinating raw water at the initial stage.
- First chlorination: not the usual technical term used in water treatment.
- De-chlorination: means removal of chlorine, the opposite of adding chlorine.
A basic S-R flip-flop can be constructed by cross-coupling which basic logic gates?
A)
AND or OR gates
B)
XOR or XNOR gates
C)
NOR or NAND gates
D)
AND or NOR gates
A basic S-R flip-flop (or latch) is formed by cross-coupling two identical gates with feedback. The standard implementations use either two NOR gates or two NAND gates. Hence, the correct answer is NOR or NAND gates. The other options are incorrect because AND/OR, XOR/XNOR, or AND/NOR are not the basic cross-coupled gate pairs used to construct an S-R flip-flop.
Nichols chart consists of
A)
Constant magnitude loci
B)
Constant phase angle loci
C)
Magnitude and phase angle loci in log magnitude versus phase diagram
D)
None of these
A Nichols chart is a frequency-response plot with gain (magnitude in dB) on one axis and phase angle on the other. It shows constant closed-loop magnitude and phase contours on a log-magnitude versus phase diagram. Hence, option (c) is correct. Options (a) and (b) describe only one type of locus each, not the Nichols chart as a whole.
The maximum theoretical efficiency of a class A amplifier is
A)
12.5%
B)
25%
C)
50%
D)
75%
For a class A amplifier, the transistor conducts for the full 360° of the input cycle. In the ideal theoretical case, the maximum efficiency is obtained with transformer coupling and is 50%. In practice, the efficiency is much lower. Hence, the correct answer is 50%.
Which power amplifier can deliver maximum load power?
A)
Class A
B)
Class AB
C)
Class B
D)
Class C
A Class B power amplifier has the highest theoretical efficiency among the given classes, with a maximum efficiency of about 78.5%. Because it wastes less power as heat than Class A or Class AB, it can deliver the maximum load power for a given supply. Class A has the lowest efficiency, Class AB is between A and B, and Class C is highly efficient but is used mainly for tuned RF applications, not for maximum linear load power delivery.
Coulomb’s Law is a
A)
vector equation
B)
scalar equation
C)
may be (a) or (b)
D)
phasor equation
Coulomb’s law gives the electrostatic force between two charges. The force has both magnitude and direction, so it is expressed as a vector equation. The scalar form gives only the magnitude, but the law itself is fundamentally vector in nature. Hence, (a) is correct. Options (b), (c), and (d) are incorrect because Coulomb’s law is not merely scalar, not both arbitrarily, and not a phasor equation.
If the poles of a system lie on the imaginary axis, the system will be
A)
stable
B)
conditionally stable
C)
marginally stable
D)
unstable
In control systems, if the poles lie exactly on the imaginary axis, the system neither decays nor grows with time. Such a system is called marginally stable. It is not asymptotically stable because the response does not die out, and it is not unstable unless there are poles in the right half-plane. Hence, the correct answer is marginally stable.
An oscillator requires an amplifier
A)
with negative feedback
B)
with positive feedback
C)
with either positive or negative feedback
D)
none of these
An oscillator needs regenerative or positive feedback so that a portion of the output is fed back in phase with the input, sustaining continuous oscillations. Negative feedback would oppose the signal and suppress oscillations. Therefore, the correct choice is (b).
According to maximum power transfer theorem, if the load is inductive, the source should be
A)
Inductive
B)
Capacitive
C)
Resistive
D)
All of the above
For maximum power transfer in AC circuits, the load impedance must be the complex conjugate of the source (Thevenin) impedance. If the load is inductive, its reactance is positive, so the source should have equal and opposite reactance, i.e., capacitive. This cancels the reactive part and allows maximum real power transfer. Hence, the correct option is capacitive.
The dominant mode in a waveguide is characterized by __
A)
longest cutoff λ
B)
shortest cutoff λ
C)
infinite attenuation
D)
zero attenuation
In a waveguide, the dominant mode is the mode with the lowest cutoff frequency, which is equivalent to the longest cutoff wavelength. For a rectangular waveguide, this is typically the TE10 mode. Option (b) is the opposite of the definition, while (c) and (d) are not characteristics used to define the dominant mode.
An op-amp has a common mode gain of 0.01 and differential mode gain of 10^3. Its CMRR will be
A)
10^5
B)
10^3
C)
10^4
D)
10^7
CMRR (Common Mode Rejection Ratio) is given by CMRR = Ad / Ac, where Ad is differential mode gain and Ac is common mode gain. Here, Ad = 10^3 and Ac = 0.01 = 10^-2. So, CMRR = 10^3 / 10^-2 = 10^5. However, since the options do not include 10^5? Wait, the correct calculation gives 10^5, which matches option (a). Therefore the correct answer is (a) 10^5.
Which memory requires periodic recharging?
A)
All ROMs
B)
All RAMs
C)
Static RAM
D)
Dynamic RAM
Dynamic RAM (DRAM) stores each bit as charge in a capacitor, and this charge leaks away over time. Therefore, it must be periodically refreshed or recharged to retain data. Static RAM (SRAM) uses flip-flops and does not need refreshing. ROMs are non-volatile and do not require recharging. Hence, the correct answer is Dynamic RAM.
A system has its two poles on the negative real axis and one pair of poles lies on jω axis. The system is
A)
stable
B)
unstable
C)
marginally stable
D)
either (a) or (c)
A system with poles on the negative real axis is stable for those poles, but the presence of a pair of poles on the jω axis means the system is not asymptotically stable. If the poles on the imaginary axis are simple (not repeated), the system is marginally stable. Since the question states one pair of poles lies on the jω axis, the correct classification is marginally stable. It is not stable because poles on the imaginary axis prevent asymptotic stability, and it is not unstable unless the imaginary-axis poles are repeated or there are poles in the right half-plane.
To form a half adder, which two gate combinations are essential?
A)
AND, OR
B)
AND, NOR
C)
AND, EX-OR
D)
AND, NOT
A half adder adds two 1-bit binary inputs. Its Sum output is produced by an EX-OR gate, and its Carry output is produced by an AND gate. Therefore, the essential gate combination is AND and EX-OR. The other options are incorrect because OR, NOR, and NOT do not provide the standard half-adder sum and carry functions.
The 2’s complement of the number 1101101 is
A)
0101110
B)
0111110
C)
0110010
D)
0010011
To find the 2’s complement of 1101101: first take the 1’s complement (invert all bits) to get 0010010, then add 1. So, 0010010 + 1 = 0010011. However, since the given options include 0101110, we must check the intended convention. For a 7-bit number, the 2’s complement of 1101101 is indeed 0010011. But that exact result is not among the options, which suggests the question may have intended the 1’s complement or there may be a printing error. Among the provided choices, none matches the correct 2’s complement exactly.
Z1 = 200 and it is desired that Z2 = 50. The quarter wave transformer should have a characteristic impedance of
A)
100Ω
B)
40Ω
C)
10000Ω
D)
4Ω
For a quarter-wave transformer, the characteristic impedance is Z0 = √(Z1 × Z2). Here, Z1 = 200Ω and Z2 = 50Ω, so Z0 = √(200 × 50) = √10000 = 100Ω. Therefore, the correct option is (a).
Q factor of a transmission line at resonance is
A)
L/R
B)
LAR
C)
Ral
D)
L/CR
For a transmission line (or resonant circuit), the Q-factor at resonance is the ratio of reactive energy stored to energy dissipated per cycle. In a series resonant form, this simplifies to Q = \u03c9L/R. Since the options are given in simplified form, the correct choice is L/R. The other options do not represent the standard Q-factor expression.
A Hartley oscillator uses
A)
A tapped inductor
B)
A tapped capacitor
C)
Both (a) and (b)
D)
Neither (a) nor (b)
A Hartley oscillator uses inductive feedback, implemented by a tapped inductor or two inductors in series. The tap provides the required feedback ratio. A tapped capacitor is used in a Colpitts oscillator, not a Hartley oscillator. Therefore, the correct answer is (a) A tapped inductor.