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Syllabus

what is modulation? what is its need.

(1) (2, 1)

(2) (2, 2)

(3) (1, 0)

(4) (0, 1)

What is meant by grating element?

(1) $\frac{F}{2}$ towards right

(2) $\frac{F}{3}$ towards left

(3) $\frac{2F}{3}$ towards right

(4) Zero

why skywave not used in the transmission of tv signals?

What is the difference between point to point and broadcast communication modes. Give one example

Q.32. If a carved black utensil is heated to high temperature and then brought in dark then :

(1) Both utensil and its carving will shine

(2) Only carving will shine

(3) Only utensil will shine

(4) None of the utensil and carving will shine

define sky wave propogationSolve this:Two identical bodies are made of a material for which the heat capacity increase with temperature. One of these is at 100

^{o}C, while the other one is 0^{o}C. If the two bodies are b ought into contact then, assuming no heat loss, the final common temperature is :(1) less than 50

^{o}C but greater than 0^{o}C (2) 0^{o}C(3) 50

^{o}C (4) more than 50^{o}Cwhy ar microwaves used in RADAR?

(1) $\frac{1}{3}\mathrm{tan}\theta $

(2) $\frac{1}{3}\mathrm{sin}\theta $

(3) $\frac{2}{3}\mathrm{tan}\theta $

(4) $\frac{2}{3}\mathrm{sin}\theta $

when modulation index is kept less than 1 distortion dosent occur.......how and why???? plxzzzzzzz reply briefly........nd fastly.......

Q). A sphere of radius 25 cm and mass 1 kg is hung by a string of negligible mass and length 40 cm, then tension in the string is :

(1) 10.81 N

(2) 18.4 N

(3) 10 N

(4) 8 N

draw a block diagram of a simple amplitude modulation.explain briefly,how amplitude modulationis achieved.

Q. Two spheres of radii in the ratio 1 : 2 and densities in the ratio 2: 1 and of same specific heat, are heated to same temperature and left in the same surrounding. Their rate of falling temperature will be in the ratio:

(1) 2 : 1 (2) 1 : 1 (3) 1 : 2 (4) 1 : 4

Explain why high frequency carrier waves are needed for effective transmission of signals?

1) 4 J

2)8 J

3)12 J

4)16 J

what is square law device? what is the function of this?Please suggest me any me hurry up!

i am wating your reply?

State two factors by which the range of TV signal can be increased??

Q). Two thermometers are used to record the temperature of a room. If the bulb of one is wrapped in wet hanky

(1) the temperature recorded by both will be same

(2) the temperature recorded by wet-bulb thermometer will be greater than that recorded by the other

(3) the temperature recorded by dry bulb thermometer will be greater than that recorded by the other

(4) none of the above

why do we need to modulate the frequency?

what are the limitations of amplitude modulation?

The block diagram of AM transmitter and AM receiver

explain detection of amplitude modulated wave

(1) $\overline{)\overline{)\mathrm{A}}.\overline{)\mathrm{B}}}=\mathrm{A}+\mathrm{B}$ (2) $\overline{)\overline{)\mathrm{A}}+\overline{)\mathrm{B}}}=\mathrm{A}.\mathrm{B}$ (3) $\overline{)\overline{)\mathrm{A}.\mathrm{B}}}=\mathrm{A}.\mathrm{B}$ (4) $\overline{)1}+\overline{)1}=1$

What is meant by detection of modulated carrier wave? Explain briefly steps for detection?

what is ground wave propagation

radius 3 R from O in which a hole of radius R is cut whose centre is at 2R distance from centre of large circular plate.

(1) R/4

(2) R/5

(3) R/2

(4) none of these

Which mode of propagation is used by short wave broadcast services having frequency range from a few MHz upto 30MHz? Expain diagrammatically how long distance communication can be achieved by this mode.Why is there an upper limit to frequency of waves used in this mode?

Sir plz..give the answer fast!!!!

Q.2. The temperature of a substance increases by 27$\xb0C$. On the kelvin scale this increase is equal to

(1) 300 K

(2) 2.46 K

(3) 27 K

(4) 7 K

Why do we use manganine wire in potentiometer?^{}^{2}in the SI system. what is the value of the moment of inertia in a system of units in which the unit of length is 5 cm and the unit of mass is 10 g?write two factors justifying the need of modulating a signal.

What's the process required to make the transmission of audio signals possible???

Are there any types???

what is square law device?

Sir, Why moon cannot be used as a communication satellite?

Q.11. What percentage of power of AM wave is carried by the side bands for modulation index m = 1 ?

I need to prepare project on Communication System ...can someone help me on it

It is based on the CBSE....and i need it for submission for the partial fullfilment for the requirement for studies in Physics 10+2.

please help me select toic or to prepare.

your help is heartly welcome at: thomasofjnv@gmail.com

before 06 november, 2012.

What is space wave propagation?

explain about downlink and uplink????

$\mathbf{8}\mathbf{.}\mathbf{}\mathrm{A}\mathrm{disc}\mathrm{rolls}\mathrm{down}\mathrm{a}\mathrm{plane}\mathrm{of}\mathrm{length}\mathrm{L}\mathrm{and}\mathrm{inclined}\mathrm{at}\mathrm{angle}\mathrm{\theta},\mathrm{without}\mathrm{slipping}.\mathrm{Its}\mathrm{velocity}\mathrm{on}\mathrm{reaching}\mathrm{the}\mathrm{bottom}\mathrm{will}\mathrm{be}:-\phantom{\rule{0ex}{0ex}}\phantom{\rule{0ex}{0ex}}\left(1\right)\sqrt{\frac{4\mathrm{gL}\mathrm{sin}\mathrm{\theta}}{3}}\left(2\right)\sqrt{\frac{2\mathrm{gL}\mathrm{sin}\mathrm{\theta}}{3}}\left(3\right)\sqrt{\frac{10\mathrm{gL}\mathrm{sin}\mathrm{\theta}}{7}}\left(4\right)\sqrt{4\mathrm{gL}\mathrm{sin}\mathrm{\theta}}$

A TV tower has a height of 100m. How much population is covered by the TV broadcast if the average population density around the tower is 1000 persons per sq km?

what is the necessity of modulation?

â€‹Q10. An object of mass M starts from rest at the bottom of a fixed incline of height H. A person decides to push the object up the incline in one of two ways with an applied force shown in the diagram. In each of the trials, the object reaches the top of the incline with speed V. How would the work done by the person on the block compare for the two trials ? Assume the same constant non-zero coefficient of kinetic friction between the incline and the object for both trails.

(A) More work would be done in Trial 1

(B) More work would be done in Trial 2

(C) It is impossible to determine for which trial there would be more work done without knowing the value of the speed V.

(D) It is impossible to determine for which trial there would the more work done without knowing the value of the coefficient of kinetic friction.

why is an FM signal less susceptible to noise than AM signal ?

Q.6. On account of the rotation of earth about its axis :-

(A) the linear velocity of objects at equator is greater than that at other places

(B) the angular velocity of objects at equator is more than that of objects at poles

(C) the linear velocity of objects at all places on the earth is equal, but angular velocity is different

(D) the angular velocity and linear velocity are uniform at all places

What is amplitude modulation?

Q. A message signal of 12 kHz and peak voltage 20 V is used to modulate a carrier wave of frequency 2 MHz and peak voltage 30 V. Calculate the (i) modulation index and (ii) side-band frequencies,

an audio signal is not transmitted directly by converting it into an electromagnetic wave of same frequency.give 2 reasons.

KINDLY PROVIDE THE SOLUTION OF PHYSICS CLASS 12 SET 55/3 OF BOARD 2013 SOON?

â€‹Q13. A solid sphere of mass m and radius R is rolling without slipping on a rough horizontal surface with angular acceleration $\alpha $. Centre of mass of sphere lies at a distance $\frac{\mathrm{R}}{\sqrt{2}}$ from the centre of sphere. Find the normal force applied by sphere on the surface at an instant when line joining centre of mass of sphere and centre of sphere makes an angle 45° with vertical and angular velocity of sphere at this instant is $\mathrm{\omega}$.

$\left(\mathrm{A}\right)\mathrm{mg}+\frac{\mathrm{mR}}{2}\left(\mathrm{\alpha}\u2013{\mathrm{\omega}}^{2}\right)\left(\mathrm{B}\right)\mathrm{mg}-\frac{{\displaystyle \mathrm{mR}}}{{\displaystyle 2}}\left(\mathrm{\alpha}+{\mathrm{\omega}}^{2}\right)\phantom{\rule{0ex}{0ex}}\phantom{\rule{0ex}{0ex}}\phantom{\rule{0ex}{0ex}}\left(\mathrm{C}\right)\mathrm{mg}+\frac{{\displaystyle \mathrm{mR}}}{{\displaystyle 2}}\left(\mathrm{\alpha}\u2013{\mathrm{\omega}}^{2}\right)\left(\mathrm{D}\right)\mathrm{mg}+\frac{{\displaystyle \mathrm{mR}}}{{\displaystyle 2}}\left(\mathrm{\alpha}+{\mathrm{\omega}}^{2}\right)$

pls explain modulation and demodulation???/

(1) double

(2) four times

(3) half

(4) remains same

draw a plot of variation of ' amplitude ' versus 'w ' for an amplitude modulated wave. hence explain the need for keeping the broadcast frequencies sufficiently spaced out ?

(1) 10 kg-${m}^{2}$

(2) 30 kg-${m}^{2}$

(3) 40 kg-${m}^{2}$

(4) 25 kg-${m}^{2}$

what is html?explain in detail?

Q. 2.In the process of modulation, new frequencies called sidebands are generated on either side (higher and lower than the carrier frequency) of the carrier by an amount equal to the highest modulating frequency. Is it possible to retrieve the message by transmitting (a) only the side bands. (b) one side band?

Q. 3. In amplitude modulation, modulation index $\mu \le 1$ is used. What will happen if $\mu 1$ ?

define frequency modulation ? write the advantages of frequency modulation over amplitude modulation ?A message signal of frequency 10kHz and peak voltage 10 V is used to modulate a carrier of frequency 1 MHz and peak voltage of 20V.Determine

a) Modulation Index

b) the side bands produced

^{8}Hz?what does line of sight communication means???

$1.\frac{\sqrt{3}}{2}m/s\phantom{\rule{0ex}{0ex}}2.3m/s\phantom{\rule{0ex}{0ex}}3.2\sqrt{3}m/s\phantom{\rule{0ex}{0ex}}4.\sqrt{3}m/s$

Why do long distance radio broadcasts use shortwave bands?

What is the principle behind the working of stethoscope? Kindly answer sir/mam.

What is sky wave propagation ?

what is modulation ?explain the amplitude modulation with the help of necessary diagram.what is meant by modulation index and the lower and upper side bands?

A diode detector is used to detect an amplitude modulated wave of 60% modulation by using a condenser of capacity 250 pico farad in parallel with a load resistance 100 kilo ohm. Find the maximum modulated frequency which could be detected by it

Difference between transducer and transmitter?

(1) 15 : 14

(2) $\sqrt{15}:\sqrt{14}$

(3) ${15}^{2}:{14}^{2}$

(4) $\sqrt{14}:\sqrt{15}$

what are logic gates??