Communication Systems Questions and Answers

A solid conducting sphere having net charge Q and radius 3 a contains a hollowed spherical region of radius 2 a A point charge Q is placed at a distance a from the common center of the spheres What is the magnitude of the electric field at the position r 4 a from the center of the spheres as marked in the figure by P a kQ a 16a 3kQ b 16 a Q 1 1 1 P kQ c 8a d can t be determined due to non uniform distribution

Transfer characteristics output voltage V vs input voltage V for a base biased transistor in CE configuration is as shown in the figure For using transistor as a switch it is used I Vol II III a in region III b both in region I and III c in region II d in region I The figura 2012

Which of the following statement is true about End Fire antenna You can select multiple correct options Only one element is driven All elements are driven Quarter wave dipoles are used Half wave dipoles are used 2

D 1101924461 NOTE SCREENSHOT PROHIBITED A B C monitoring and recording by usi D ID 1101924461 barcode ID 1101924461 Active RF ID ID 1101924461 Passive RF ID ID 1101924461

1101924461 NOTE SCREENSHOT PR ID 1101924461 3 C D software as a service ID 1101924461 service as a software ID 1101924461 service as a service ID 1101924461

Since diodes are destroyed by circuits must have Select one a higher current sources b more dopants c higher voltage sources O d current limiting resistors O

If a capacitor of capacitance P 0 05 J 2 1 J 3 0 005 J A capacitor is connected to a cell of emf E having some internal resistance r The potential difference across the 1 cell is E 2 cell is E RPMT 2006 3 capacitor is E 4 capacitor is E dy JEE Main NEET AIIMS 74

A semiconductor X is made by doping a germanium crystal with arsenic Z 33 A secon semiconductor Y is made by doping germanium with indium Z 49 The two are joined en to end and connected to a battery as shown Which of the following statements is correct X Y Question Type Single Correct Type 1 X is P type Y is N type and the junction is forward biased 2 X is N type Y is P type and the junction is forward biased 3 X is P type Y is N type and the junction is reverse biased 4 X is N type Y is P type and the junction is reverse biased

a Be b 40 In a full wave rectifier circuit operating from 50 Hz mains frequency the fundamental frequency in the ripple would be a 25 Hz b 50 Hz c 70 7 Hz d 100 Hz 1 Two simple harmonic motions are represented by the

JEE Advanced 2019 Two identical moving coil galvanometers have 10 resistance and full scale deflection at 2 A current One of them is converted into a voltmeter of 100 mV full scale reading and the other into an Ammeter of 1 mA full scale current using appropriate resistors These are then used to measure the voltage and current in the Ohm s law experiment with R 1000 22 resistor by using an ideal cell Which of the following statements s is are correct 1 The measured value of R will be 978 9 R982 Q 2 The resistance of the ammeter will be 0 02 2 round off to 2nd decimal place If the ideal cell is replaced by a cell having internal resistance of 5 2 then the measured value of R will be more than 1000 S 3 4 The resistance of the voltmeter will be

The modulation frequency of an AM radio station is 250 kHz which is 10 of the carrier wave If another AM station approaches you for license what broadcas frequency will you allot 1 2750 kHz 3 2250 kHz 2 2900 kHz 4 2000 kHz

Which of the following gates will have an output of 0 00 C 1 d Question Type Single Correct Type 2 a 3 b 00 10 4 c 00 00 b 6

When we place PLC programming such that it gives warning wher room s lights off out of 4 rooms and light controlling unit should gi warning then what is expression ACD ABD ABC BCD OAB BC AD AC ABC AB BC CD AC AD BD ABCD

28 In total internal reflection when the angle of incidence is equal to the critical angle for the pair of media in contact what will be angle of refraction 1 180 12 00 0 3 Equal to angle of incidence 10 4 90 m from the

Which of the following is the feature of switch 4 It operates on physical layer It broadcasts data to every computer or Ethernet based device connected to it It is an intelligent network device that can be conceived as a multiport network bridg O When a packet arrives at one port it is copied to the other ports so that all segments of the LAN can see all packets

Identify the correct statement regarding Topologies of network You can select multiple correct answers In a mesh topology installation and management are easy In a ring topology if one of the nodes are damaged it will damage the whole network Star Topology all the nodes are connected to one single node known as the central node In a bas topology If the main cable gets damaged it will not effect the whole network

Pick up the correct statement regarding bandwidth delay product The time required for transmission of message depends on the size of the message OIt is queuing time needed for each intermediate time O Bandwidth and delay are two performance matrix of a link O Its is time how long it takes for an entire message to Lompletely arrive at the destination

Identify the correct statements in context of presentation layer Statement 1 In this layer the number of bits contained in the information is reduced Statement 2 It determines the transmission speed in network O Statement 1 and Statement 2 both are correct Statement 2 is correct Statement 1 and Statement 2 both are incorrect Statement 1 is correct

Computer X can communicate with computer Y by using DNS protocol and at the same time X communicate with computer Z by using SMTP for this process which addressing is used O Port addressing O Logical addressing O process addressing O Physical addressing 4

A network with bandwidth of 10 Mbps can pass only an average of 24 000 frames per minute with each frame carrying capacity an average of 10 000 bits What is throughput of network O 12 Mbps 3 Mbps

Two trains A and B of length 400 m each are moving on two parallel tracks wit uniform speed of 72 km h in the same direction with A ahead of B The drive B decides to overtake A and accelerates by 1 m s2 If after 50 s the guard of B brushes past the driver of A what was the original distance betw

PCM signal is called as O The signals which are obtained by encoding each quantized signal into a quantized word The signals which are obtained by encoding each quantized signal into a analog word The signals which are obtained by encoding each quantized signal into a sampled word O The signals which are obtained by encoding each quantized signal into a digital word

18 In the circuit shown the value of of the transistor is 48 If the base current supplied is 200 A what is the voltage at the terminal Y a 0 2 V b 0 5 V c 4 V d 4 8 V Vcc 5V gy 500 S IB 200 A Y 2020

Here Al M I of detached mass For asymmetrical attachment radius of gyration will be ation 7 9 M m q I mr M L I m r 11 Illustrations hout avis a 2 I mr K M m b and c d a K change 1 kg 1 m 2 kg 3 kg 4 S

4 The hagram shown below depicts the incidence of Radio waves falling at angle a to vertical The waves are received directly by a ladder after reflection from a nearby liquid surface The value of h from the liquid surface so that it records a maximum intensity a maxima wavelength A is N ycosa The value of y is Hy

A uniform slender bar AB of mass m is suspended from two springs as shown If spring 2 breaks determine at that instant 2 30 B a the angular acceleration of the bar b the acceleration of point A c the acceleration of point B A 30 K L3 13 1 3 B

When a certain weight is suspended from a long uniform wire its length increases by one cm If the same weight is suspended from another wire of the same material and length but having a diameter half of the first one then the increase in length will be 1 0 5 cm 2 2 cm 3 4 cm 4 8 cm

Statement 1 In reverse blocking mode of SCR the device behaves as if two diodes are connected in series with reverse voltage applied across them Statement 2 In forward blocking mode avalanche breakdown happened in SCR Statement 2 is correct Statement 1 is correct and Statement 2 both are incorrect Statement 1 is correct Statement 1 is correct and Statement 2 both are correct

Identify the correct statements regarding Class E commutation You can select multiple correct options The peak value of the current pulse must be more than the load current In class E commutation a pulse of current is obtained from a separate voltage source to turn off the conducting SCR L External pulse commutation load current is reverse biased by the ac source voltage and the device is turned off when anode current falls below the holding current Only one supply Vs is required to turn on thyristor and load is connected to source Vs

In order to protect thyristors against high dv dt rating which of the following circuit is used Series Equalizing Circuit both Series and Dynamic Equalizing Circuit Static Equalizing Circuit

The contents of register Accumulator A and B are 8DH and 9FH respectively of 8085 microprocessor What will be the contents of A and sign flag S after executing SUB B instruction CO2 O A EE S 1 O A OF S 1 O A OF S 0 O A EE S 0

What will be contents of 8085 accumulator after execution of the following program If data present at location 3000 is OFH and at 3001 is 03H CO2 LXI H 3000 MOVA M INX H MOV B M ADD B HLT O 18 O F3 O 12

When the following program is executed on 8085 processor at the completion of execution of program what will be the stack pointer contains CO2 Memory Address in Hex 2050 2053 2054 2055 2058 2059 O 1049 O104C O 1048 Instructions LXI SP 1050 PUSH B PUSH D CALL 4050 POP H HLT

O Increase the information transmission rate Use only one carrier frequency to handle different signals To use different frequency bands for different signals To protect all small signals in PCM from quantizing noise

In digital communication role of Channel encoder is To convert analog information signal to digital signal Add redundant bits to digitally converted information code To convert digital signal signal to analog information To modulate information signal

The alternative used to avoid 10 power consumption issues is ID 1101924461 NOTE SCREENSHOT PROHIBITED ID 1101924461 A O B O C O D O Use Battery Power ID 1101924461 Energy Harvesting ID 1101924461 Use External Energy ID 1101924461 Use Generator

Which one of the following statements is wrong O Radio waves in the frequency range 10MHz to 20 MHz are called sky waves Radio horizon of the transmitting antenna for space wave is dT RhT R radius of earth h height of transmitting antenna O Fiber optical communication is almost free from electrical disturbances The principle of fibre optical communication is total internal reflection

Anisotropic point source of light of power P is kept in front of a screen which has a circular hole of radius R as shown in figure 1 Power crossing the circular hole is P Now a transparent cylinder which does not absorb any light of a refractive index u 21 is introduced between the source and screen and kept as shown in figure 2 Consider the following two cases Case 1 Source is kept on the ans of the cylinder just outside the cylinder Case 2 Source is kept on the aos of the cylinder just inside the cylinder In case 1 power crossing the circular hole is P and in case 2 it is P 3R Figure 1 Answer the following two questions Value of P is 2P A 2 3 Value of P is 2 2 A P 2 3 2R B 2 3 B P 2 2 3 d 3R J Figure 2 C C P 2P 2 2 2 3 R2R 2 3 D P 2 2 2 3 75 JL

A particle of mass m is projected with velocity u making an angle 45 with horizontal ground The torque and angular momentum about topmost point when the projectile is at maximum height mu mu 2 mu mu 3 Ta o 4 None

They are fire fox Protection from animal La Source of lighting iv They use fire fox Heat k How were microliths made Name two tools of this type Answer in about 100 words Fynlain any four reasons as to why hunter gatherers had to move from place to place

Jasmine who is always in great mood in the morning arrives in class singing If the frequency of the sound waves she is producing is 874 H and the speed of sound in our classroom is 348 m s determine a Temperature in our classromm b The wavelength of the sound waves c The length of a closed tube that would produce the second resonant length Each question answered is worth K 4 T 6 C 8 A6

Two balls of equal masses m each undergo oblique collision If collision is perfectly elastic then angle between their velocities after collision is 1 K4 It 2 13 10

Three amplifiers X Y and Z are connected in series cascaded If the voltage gains of X Y and Z are 10 20 and 30 respectively and the input signal is 1 mV Peak value then the output signal voltage Peak value will be 6 V 60 V 0 6 V

1 61A Find various orders of Bragg 5 b Carbon is allowed to diffuse through a steel plate 10 mm thick The concentrations of carbon a the two faces are 0 85 and 0 40 kg m which are maintained constant If the preexponential and activation energy are 6 2 x 10 7 and 80 000 J mol respectively compute the temperature at whic the diffusion flux is 6 3 10 10 Kg m s 4 biomotric and non stoichiometric defects 2

The two sections of an 11 kV busbar are connected by a reactor with a through load rating of 25 MVA and a reactance phase of 10 based on 25 MVA Each section is connected by a 20 MVA transformer having a reactance of 10 on 20 MVA to a 33 kV busbar which is not sectionalized Connected to this 33 kV busbar are two generator transformer sets each rated at 37 5 MVA and each having a total reactance of 25 on 37 5 MVA The 33 kV busbar is connected to the 132 kV grid bus by two identical transformers in parallel each rated at 45 MVA and having a reactance of 12 5 on 45 MVA The 3 phase fault level infeed from the grid is 2000 MVA a Calculate the 3 phase fault level MVA at the 11 kV busbar with and without the reactor reactor short circuited and at 33 kV busbar

17 When a low lying aeroplane passes overhead e sometimes notice a slight shaking of the picture on ur TV screen This is due to a diffraction of the signal received from the antenna b interference of the direct signal received by the antenna with the weak signal reflected by the passing aircraft c change of magnetic flux occurring due to the passage of aircraft d vibrations created by the passage of aircraft

Choose the basic condition to be satisfied for the transmission of light through an optical fibre i Light must travel from denser to rarer medium ii Light must travel from rarer to denser medium iii Light must travel in same medium iv Angle of incidence in the denser medium must be lesser than the critical angle v Angle of incidence in the denser medium must be greater than he critical angle vi Angle of ncidence in the denser nedium must be equal to ritical angle i and iv only iii and vi only i and v only ii and vi only 1 point

12 The amplifiers A B and C are connected in series If the voltage gain of A B and C are 10 15 and 20 respectively and input signal 2 mV peak value Then the output signal voltage s peak value will be 1 6 V 2 5V

A parallel plate capacitor without dielectric is charged by a battery and kept connected to the battery A dielectric slab of dielectric constant K is inserted between the plates fully occupying the space between the plates The energy density of electric field between the plates will 1 Increase K2 times 2 Decrease K times 3 Increase K times

m The process of superimposing a low frequency signal on high frequency carrier wave for long distance transmission is known as a demodulation c amplification b modulation d attenuation