MPPGCL JE Electronics Mock Test - 10 Free Online Test 2026

The following circuit is of a: Bubble AND gate

Key Points

Alternative Logic Gates:

An alternative logic gate is an alternate logic gate that produces the same output as the original logic gate and can be used during the unavailability of the original logic gate to serve the same purpose.

• Alternative logic gates are also called as Alternate Gates.
• Alternative logic gates are also called as Bubbled Gates since they contain bubbles in them.

Fire Control Room

• For all buildings 15 m in height and above and apartment buildings with a height of 30 m and above, there shall be a Control Room on the entrance floor of the building with a communication system (suitable public address system) to all floors and facilities for receiving the message from different floors.
• Details of all floor plans along with the details of fire fighting equipment and installations shall be displayed in the fire control room.
• The fire control room shall also have facilities to detect the fire on any floor through indicator boards connection; fire detection and alarm systems on all floors.
• The fire staff in charge of the fire control room shall be responsible for maintenance of the various services and the fire fighting equipment and installations in coordination with security, electrical and civil staff of the building.

A programmable logic controller (PLC) or programmable controller is an industrial digital computer which has been adopted for the control of manufacturing processes, such as assembly lines, or robotic devices, or any activity that requires high-reliability control and ease of programming and process fault diagnosis.

Early (PLC) was designed to replace relay logic systems. These PLCs were programmed in "ladder logic", which strongly resembles a schematic diagram of relay logic.

Concept:

Astable multivibrator:

It is also known as a square wave generator. 

In astable multivibrator, 

T = T_on + T_off 

T_on = 0.69 (R_a + R_b)C , and  T_off = 0.69 (RbC) 

T = 0.69 (2R_b + R_a)C

Output frequency is given by 

Analysis:

Given circuit diagram is a stable multivibrator or a square wave generator.

The current gain β of the transistor is given by:

D_E: Diffusion constant of minority carriers in the emitter

D_B: Diffusion constant of minority carries in Base

N_E: emitter doping concentration

N_B: Base doping concentration

L_E: Length of diffusion of minority carriers in emitter

W_B: Base width.

 ratio of conductivity from emitter to base = 10 (Given)

LE_n (minority carries in emitter)  (hole diffusion length in base)

Taking the case of Si:

β = 2.1 × 10 × 5 = 105

Taking case of Si:

β = 2.6 × 10 × 5 = 130

None of the given option match, but if we check the option by satisfying the relation  

Only option 1 is satisfying

Hence option 1 is correct.

Concept:

The electric field for an isotropic antenna varies with the distance as given:

1/r term is the most dominant. 

Calculation:

Given,

E = 3 V/m for r = R

For r₂ = 3R,

Electric field E₂ will be 

Concept:

• When an alternating magnetic field is applied to a magnetic material, an emf is induced in the material itself according to Faraday’s law of Electromagnetic induction.
• Since the magnetic material is a conducting material, these EMF’s circulates current within the body of the material. These circulating currents are called Eddy currents. They are produced when the conductor experiences a changing magnetic field.

Eddy current loss in the transformer is given by:

P_e = K_e B_m². t². f². V Watts

Where;

K - coefficient of eddy current. Its value depends upon the nature of magnetic material

Bm - Maximum value of flux density in Wb/m2

t - Thickness of lamination in meters

f - Frequency of reversal of the magnetic field in Hz

V - Volume of magnetic material in m3

Moving Iron Instrument

• MI instruments are used for the measurement of the RMS value of current and voltage.
• These instruments have a non-uniform scale.
• It works on the principle of attraction of a single piece of soft iron into the magnetic field.
• In the MI instrument, when the current is passed through the solenoid, a magnetic field is set up inside the solenoid. Then the iron piece gets magnetized which in turn deflects the pointer. 
• The deflecting torque produced is directly proportional to the square of the current.
• The controlling torque is provided by the spring control.
• The damping torque is provided by air friction damping.

The correct answer is Remote sensing.

• IRS series satellite is used for Remote sensing.

Key Points

• The Indian Remote Sensing (IRS) system is the largest constellation of remote sensing satellites for civilian use in operation today in the world, with 11 operational satellites.
• All these are placed in polar Sun-synchronous orbit and provide data in a variety of spatial, spectral, and temporal resolutions.
• Indian Remote Sensing Programme completed its 25 years of successful operations on March 17, 2013.
• IRS data applications:
  • Drought monitoring and assessment based on vegetation condition.
  • Flood risk zone mapping and flood damage assessment.
  • Hydro-geomorphological maps for locating underground water resources for drilling well.
  • Irrigation command area status monitoring.
  • Snow-melt run-off estimates for planning water use in downstream projects.
  • Land use and land cover mapping.
  • Urban planning.
  • Forest survey.
  • Wetland mapping.
  • Environmental impact analysis.

​Additional Information

• ​Following are the remote sensing satellites planned by ISRO to be launched:
  • RESOURCESAT-3
    • A follow on to Resourcesat-2, it will carry a more advanced LISS-III-WS (Wide Swath) Sensor having similar swath and revisit capability as Advanced Wide Field Sensor (AWiFS).
    • The satellite would also carry Atmospheric Correction Sensor (ACS) for quantitative interpretation and geophysical parameter retrieval.
    • It slated to be launched in 2021.
  • OCEANSAT-3
    • Oceansat-3 would carry Thermal IR Sensor, 12 channel Ocean Color Monitor, Scatterometer, and Passive Microwave Radiometer.
    • IR Sensor and Ocean Color Monitor would be used in the analysis for operational Potential Fishing Zones.
    • Satellite is mainly for Ocean biology and sea state applications.
    • It is slated to the launched aboard PSLV in January 2020.
  • GISATs
    • GISAT-1 is planned for launch in May 2020 and GISAT-2 is planned for launch in August 2020. 
    • They are expected to provide images from geostationary orbit during disasters. 

The correct answer is option "4"
Concept:

The  power consumption is given by 

P =V² / R watts as the voltage across it will be constant.

where 

V is voltage in Volts

R is the resistance

Calculation:

R₁ = 2000 Ω

P₁ =  2 mW

P = V²/R₁

V² = PR₁ = 2 × 10^-3 × 2000 = 4 V

V = 2 V

for R₂ = 4000 Ω

P = V²/R₂

= 2² / 4000 = 1 mW

Short-channel effect in MOSFET:

• If the channel length of MOSFET becomes comparatively equal to the depletion layer widths of source and drain junction then it is called that MOSFET suffers from short-channel effect.
• Due to this effect, the following parameters are affected
• Mobility of charge carrier in the channel
• The threshold voltage changed due to a shorter length of the channel.
• Drain current also changed as threshold voltage changed

So, based on the above points all statements are true

Concept:

According to Kirchhoff’s current law (KCL), the algebraic sum of the electric currents meeting at a common point is zero. I.e. the sum of currents entering a node is equal to the sum of currents leaving the node. It is based on the conservation of charge.

Mathematically we can express this as:

Where i_n represents the n^th current

Calculation:

Now by applying KCL

I + 0.4 I = 14 A

1.4 I = 14 A

⇒ I = 10 A

Additional Information

Kirchhoff’s voltage law (KVL), the algebraic sum of all the voltages around any closed path is zero. It is based on the conservation of energy.

Mathematically we can express this as:

Where V_n represents the n^th Voltage

Concept:

Z parameter:

We will get the following set of two equations by considering the variables V₁ & V₂ as dependent and I₁ & I₂ as an independent. The coefficients of independent variables, I₁ and I₂ are called Z parameters.

V₁ = Z₁₁I₁ +Z₁₂I₂

V₂ = Z₂₁I₁+ Z₂₂I₂

Calculation:

Apply KVL on loop 1:

⇒ V₁ = 5I₁ + 20(I₁ + I₂)

⇒ V₁ = 25I₁ + 20I₂ ------------ (1)

Apply KVL on loop 2:

⇒  V₂ = 10I₂ + 20(I₁ + I₂)

⇒ V₂ = 20I₁ + 30I₂ -------------(2)

Compare equation 1 and 2 with Z parameter equations:

 Z₁₁ = 25Ω, Z₂₂ = 30Ω

Alternate Method 
For a T equivalent network as shown below 

Z₁₁ = (Z₁ + Z₃) = (5+20) = 25Ω 

Z₂₂ = (Z₂ + Z₃) = (10 + 20) = 30Ω 

Z₁₂ = Z₂₁ = Z₃ = 20Ω 

Radiated power(P) is a measure of how much power is radiated by an antenna when the antenna is connected to a transmitter.

Radiated resistance(R) is the component of antenna resistance that accounts for the power radiated into space and is equal in ohms.

Power radiated by an antenna is calculated by using formula,

P= I²× R

P = (6 × 6) × 200

P = 36 × 200

P = 7200 W

• An encoder is a device that converts numbers, characters, or symbols into a coded format.
• Decimal-to-BCD encoder is the type of encoder that usually consists of ten input lines and 4 output lines.
• Each input line corresponds to each decimal digit and 4 outputs correspond to the BCD code which is represented in 4 bits.
• This encoder accepts the decoded decimal data as an input and encodes it to the BCD output which is available on the output lines.
• The block diagram of a Decimal-to-BCD encoder is as shown:

​

Important Point

Different types of other encoders include:

• 4-to-2 Binary Encoder (4 inputs and 2 coded outputs)
• Octal to Binary Encoder (Eight inputs and 3 coded outputs)
• Keyboard Encoder

The correct answer is "Output Device".

Key Points 

• Printer-
  • It is a computer peripheral machine (output device) that prints graphics or text, usually on paper.
  • There are different types of printers available. They are- 3D printers, inkjet printers, laser printers, and thermal printers.

Additional Information

• Output Device-
  • An output device is any piece of computer hardware that converts information into a human-perceptible form or, a physical machine-readable form for use.
  • The computer monitor is the most common output device.
  • For example- Printer, Plotter, Projector, etc.
• Input Device-
  • In computer terminology, Input Device is a piece of equipment used to feed data and signals to an information processing system, such as a computer.
  •  For example- keyboards, mouse, scanners, cameras, joysticks, microphones, etc.
• Data Generator-
  • It generates data according to some pattern instead of reading data from a file, databases, or any other data source. 

In satellite communication, uplink and downlink frequencies are kept different.

Uplink frequency > Downlink frequency

Hence, option C is correct.

Explanation:

• The transmission of a signal from the first earth station to satellite through a channel is called uplink​.
• The transmission of a signal from the satellite to the second earth station through a channel is called the downlink.
• Uplink frequency is the frequency at which, the first earth station is communicating with the satellite.
• The satellite transponder converts this signal into another frequency and sends it down to the second earth station.
• This frequency is called Downlink frequency. In a similar way, the second earth station can also communicate with the first one

In the atmosphere, the attenuation is directly proportional to frequency.

Since the satellite cannot afford to have high powers downlink is sent at lower frequencies, while the station at earth can afford to transmit at high frequencies.

Concept:

Symbol rate

• The symbol rate is measured in baud (Bd) or symbols per second.
• In the case of a line code, the symbol rate is the pulse rate in pulses per second.
• Each symbol can represent or convey one or several bits of data.
• The symbol rate is related to the gross bitrate expressed in bits per second.

A symbol may consist of one or more bits as determined by the modulation format.

In a BPSK system, each symbol represents 1 bit; in a QPSK system, each symbol represents 2 bits. The Baud Rate (BR) is given by:

Calculation:

Given modulation technique is 16 QAM

The number of QAM states is 2^N, as determined by the number of binary bits per symbol.

Thus a 16-QAM system (N = 4) is one for which the (microwave) carrier is modulated into any one of 16 different amplitude and phase states

• FSK is a system of frequency modulation in which the nominal unmodulated carrier frequency corresponds to the mark condition, and space is represented by a downward frequency shift
• In the FSK generator, the frequency shift may be obtained by applying the varying dc output of the telegraph machine to a varactor diode in a crystal oscillator
• At the receiving end, the signal is demultiplexed and applied to a standard phase discriminator
• This is how a telegraph works with FSK modulation

The smaller the signal strength, the stronger it is hit by the quantization process. Companding is used to protect these small strength signals from quantization noise.

Companding:

• Companding, also known as Companded PCM, is a non-uniform quantization technique.
• It is implemented to improve the signal to quantization noise ratio of weak signals.
• The compression of the signal at the transmitter and expansion at the receiver is combined to be called companding. This is shown in the form of a block diagram:

• Companders like A-law and μ-law Companders are used in PCM to compress signals before input to the ADC in the transmitter stage and expand it after the input to DAC at the receiver.

The z-transform for 1/n does not exist for n=0, but it exists for n > 0 and for n < 0

Let n > 0

X(z) = 

Differentiating both sides w.r.t z we get,

   |z-1| < 1 or |z| > 1

Integrating both sides, we get

 for |z| > 1

Let n < 0

X(z) = 

Differentiating both sides w.r.t z we get,

Let n = -p

     |z| < 1

Integrating both sides, we get

 for |z| < 1

∴ By looking at the options the correct answer is 3 (given for n > 0)

Concept:

Sampling Theorem: According to the sampling theorem, for the signal to be recovered back, the minimum sampling rate required for sampling any signal is the Nyquist sampling rate which is twice the maximum band of frequency.

Effect of scaling:

The scaling in the time domain results in an inverse of scaling in the frequency domain, i.e.

For a signal x(t) bandlimited to f_m Hz, the signal x(at), will be bandlimited to (a × f_m) Hz.

Calculation:

We are given a signal x₁(t) is band limited to 4π rad/sec then signal x₁(2t) will band limited to:

This is because x(2t) is the compressed version of x(t) and hence in the frequency domain the spectrum will expand.

Similarly, for signal x₂(t), band-limited to 10π rad/sec, x₂(t/2) will band limited to:

This is because x(t/2) is the expanded version of x(t) and hence in the frequency domain the spectrum will get compressed.

Now a signal x(t) = x₁(2t) + x₂(t/2) will be bandlimited to 8π rad/sec.

The Nyquist or minimum sampling rate of signal x(t) will twice the maximum rate present in it, i.e.

Nyquist rate = 2 × 8π rad/sec

Concept:

Some important Laplace transforms are:

The general expression of an amplitude-modulated wave for a single-tone message signal is given as:

s_AM(T) = [A_c + A_mcosω_mt] cosω_ct

where ω_m = Frequency of the message signal

ω_c = Carrier signal frequency

The expression can be written as:

s_AM(T) = A_c cosω_ct + A_mcosω_mtcosω_ct

We observe that the amplitude modulated signal has both the carrier frequency and the shifted frequency as shown:

The correct answer is 'option 2'

Solution:

In moving-coil instruments, the deflection is directly proportional to the current. i.e. θ ∝ I.

∴ The scale used in the moving coil instruments is linear in nature.

Additional Information

• In thermocouple instruments, the deflection is directly proportional to the square of the current. i.e. θ ∝ I²
• In moving iron instruments, the deflection is directly proportional to the square of the current. i.e. θ ∝ I²
• In hotwire instruments, the deflection is directly proportional to the square of the current. i.e. θ ∝ I²

Given: 

R_b = 4 kbps

In FSK, the best possible interval between the carriers is given as:

ΔT = 0.5 msec

Important Point

FSK (Frequency Shift Keying):

In FSK (Frequency Shift Keying) binary 1 is represented with a high-frequency carrier signal and binary 0 is represented with a low-frequency carrier, i.e. In FSK, the carrier frequency is switched between 2 extremes.

For binary ‘1’ → S₁ (A) = Acos 2π f_Ht

For binary ‘0’ → S₂ (t) = A cos 2π f_Lt . The constellation diagram is as shown:

ASK(Amplitude Shift Keying):

In ASK (Amplitude shift keying) binary ‘1’ is represented with the presence of a carrier and binary ‘0’ is represented with the absence of a carrier:

For binary ‘1’ → S₁ (t) = Acos 2π f_ct

For binary ‘0’ → S₂ (t) = 0

The Constellation Diagram Representation is as shown:

where ‘I’ is the in-phase Component and ‘Q’ is the Quadrature phase.

PSK(Phase Shift Keying):

In PSK (phase shift keying) binary 1 is represented with a carrier signal and binary O is represented with 180° phase shift of a carrier

For binary ‘1’ → S₁ (A) = Acos 2π f_ct

For binary ‘0’ → S₂ (t) = A cos (2πf_ct + 180°) = - A cos 2π f_ct

The Constellation Diagram Representation is as shown:

R is brother of P, who is husband of Q. So, R is brother-in-law of Q.

• Lump sum: a single payment made at a particular time, as opposed to a number of smaller payments or installments.
• Strong: having the power to move heavy weights or perform other physically demanding tasks.
• Little: small in size, amount, or degree.
• Huge: extremely large; enormous.
• Massive: exceptionally large.

So, the synonym of Massive is Huge.