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Assignments to IT branch

ENGINEERING GRAPHICS

SHEET NO: 2( CONICS)

1. The minor axis of an ellipse is 70mm and the distance between its focal points is also 70mm. Using a geometrical construction, draw the ellipse, full size showing all necessary construction lines.
2. Draw an ellipse with major axis 80mm and minor axis 60mm .Also draw one parallel curve, out side the original ellipse, and 18mm away from it.
3. Draw an ellipse with major axis AB= 120mm and the minor axis CD = 80mm. the centre lines formed by the major and minor axes intersect at the point ‘O’. Mark the foci of the ellipse on the line AOB. Point P lies on the ellipse such that the angle AOP= 45^0. Draw the tangent and normal at point P.
4. A stone thrown up in the air reaches a maximum height of 120m and falls at a point 90m away, horizontally. Trace the path of the stone, assuming it to be a parabolic. Take a suitable scale.
5. A cricket ball is thrown from a building, 7 m high and at the highest point of flight, it just passes over a palm tree 14m high. Draw the path traced by the ball if the distance between the palm tree and building is 3.5 m. use a scale of 1: 100.
6. Two points F1 and F2 are located on a plane sheet of paper and are 100mm apart. A point P moves on the sheet such that the difference of its distances from F1 and F2 always remained 50mm. find the locus of P? Draw a tangent and normal to the locus at any general point.

7. Two straight lines OA and OB make an angle of 75⁰ between them. P is a point 30mm from OA and 40mm from OB. Draw a hyperbola through P, with OA and OB as asymptotes marking at least 12 points.

SHEET NO 3(MISCELLANEOUS CURVES)

1. A circular wheel of 600mm diameter rolls without slipping along a straight surface. Draw the curve traced by a point P on its rim for 1.5 revolutions of the wheel. Name the curve traced.

2. A wheel of 50mm diameter rolls without slipping in two straight lines in two stages. For the first half of the revolution of the wheel, it rolls on a vertical line. In the second half it rolls on a line inclined at 40 ⁰ to the vertical. Draw the complete curve traced out by a point P on the circumference initially touching the vertical line in one revolution.

3. A motor cyclist drives his motor cycle in a globe of 4m diameter. The diameter of the motor cycle wheel is 80 cm .Draw the locus of a point spot on the circumference of the wheel for one revolution on the maximum diameter path in the globe

4. A string is completely wound around the circumference of a semi circular cylinder of 60 mm diameter holding the free end of the string such that the string is all the time held taut, it is unwound completely. Trace the path followed by the free end. Also name the curve

5. Draw an Archimedean spiral for 1.5 convolutions .the spiral starts from the pole and its greatest radius is 70mm .Draw the tangent to the curve at appoint 30mm from the pole

6. Construct a logarithmic spiral for one convolution given the length of shortest radius as 15mm and the ratio of the lengths of successive radius vectors enclosing an angle of 30 ⁰ as 9:8

Happy christmas friend

happy christmas to every cemp friend,

May this Christmas be so special that you never ever feel lonely again and be surrounded by loved ones throughout!

Data Communications basics

Data Communications Basics

Contents(click on the titles below to get detailed notes)

1. What is Data Communications?
2. Communications Channels
3. Serial Communications
4. Asynchronous vs. Synchronous Transmission
5. The ASCII Character Set
6. Parity and Checksums
7. Data Compression
8. Data Encryption
9. Data Storage Technology
10. Data Transfer in Digital Circuits
11. Transmission over Short Distances (< 2 feet)
12. Noise and Electrical Distortion
13. Transmission over Medium Distances (<>
14. Transmission over Long Distances (<4000 feet)
15. Transmission over Very Long Distances (> 4000 feet)

resources for assignments!!

For chemistry .students who got the topic Weston CELL ..
Electrochemistry

Electrochemistry is a branch of chemistry that studies chemical reactions which take place in a solution at the interface of an electron conductor (a metal or a semiconductor) and an ionic conductor (the electrolyte), and which involve electron transfer between the electrode and the electrolyte or species in solution.
Electrochemical cell
An electrochemical cell is a device used for generating an electromotive force (voltage) and current from chemical reactions. The current is caused by the reactions releasing and accepting electrons at the different ends of a conductor. A common example of an electrochemical cell is a standard 1.5-volt battery. Batteries are composed of usually multiple Galvanic cells.
Wet cell

A wet cell is a galvanic electrochemical cell with a liquid electrolyte. A dry cell, on the other hand, is a cell with a pasty electrolyte. Wet cells were a precursor to dry cells and are commonly used as a learning tool for electrochemistry. It is often built with common laboratory supplies, like beakers, for demonstrations of how electrochemical cells work. A particular type of wet cell known as a concentration cell is important in understanding corrosion. Wet cells may be primary cells (non-rechargeable) or secondary cells (rechargeable).
Primary wet cells

Primary wet cells are the Leclanche cell, Grove cell, Bunsen cell, Chromic acid cell, Clark cell and Weston cell.
Weston cell

The Weston cell, invented by Edward Weston in 1893, is a wet-chemical cell that produces a highly stable voltage suitable as a laboratory standard for calibration of voltmeters. It was adopted as the International Standard for EMF in 1911.
Chemistry


The anode is an amalgam of cadmium with mercury, the cathode is of pure mercury, the electrolyte is a solution of cadmium sulfate and the depolarizer is a paste of mercurous sulfate.
As shown in the illustration, the cell is set up in an H-shaped glass vessel with the cadmium amalgam in one leg and the pure mercury in the other. Electrical connections to the cadmium amalgam and the mercury are made by platinum wires fused through the lower ends of the legs.
Unsaturated Weston cells, such as this example, are the most common voltage standards in normal laboratory use. This specimen represents a style going back to at least 1929. These cells show a small temperature coefficient and so are normally preferred over the saturated Weston cell. However their e.m.f. decreases by about 0.08 mv per year, and thus must be calibrated periodically against a saturated Weston cell at a defined temperature. The Weston cell may be diagramed as:

Cd(Hg) | CdSO4(aq), Hg2SO4 | Hg.


Unsaturated Weston cells, such as this example, are the most common voltage standards in normal laboratory use. This specimen represents a style going back to at least 1929. These cells show a small temperature coefficient and so are normally preferred over the saturated Weston cell. However their e.m.f. decreases by about 0.08 mv per year, and thus must be calibrated periodically against a saturated Weston cell at a defined temperature. The Weston cell may be diagramed as:

Cd(Hg) | CdSO4(aq), Hg2SO4 | Hg.

Weston invented and patented the saturated cadmium cell in 1893. It had the advantage of being less temperature sensitive than the previous standard, the Clark cell. It also had the advantage of producing a voltage very near to one volt: 1.0183 V. In 1911 the Weston Saturated Cadmium Cell became the International Standard for electromotive force. Weston waved his patent rights shortly afterword so anyone was allowed to manufacture it.
Back in the early days of electrical measurement technology, a special type of battery known as a mercury standard cell was popularly used as a voltage calibration standard. The output of a mercury cell was 1.0183 to 1.0194 volts DC (depending on the specific design of cell), and was extremely stable over time. Advertised drift was around 0.004 percent of rated voltage per year. Mercury standard cells were sometimes known as Weston cells or cadmium cells.
Disadvantages

Unfortunately, mercury cells were rather intolerant of any current drain and could not even be measured with an analog voltmeter without compromising accuracy. Manufacturers typically called for no more than 0.1 mA of current through the cell, and even that figure was considered a momentary, or surge maximum! Consequently, standard cells could only be measured with a potentiometric (null-balance) device where current drain is almost zero. Short-circuiting a mercury cell was prohibited, and once short-circuited, the cell could never be relied upon again as a standard device.

Now electrical assignment working of single phase meter.

Construction of induction type energy meter

Induction type energy meter essentially consists of following components

(a) Driving system (b) Moving system (c) Braking system and (d) Registering system.
• Driving system: The construction of the electro magnet system is shown in Fig. 44.1(a) and it consists of two electromagnets, called “shunt” magnet and “series” magnet, of laminated construction.
A coil having large number of turns of fine wire is wound on the middle limb of the shunt magnet. This coil is known as “pressure or voltage” coil and is connected across the supply mains. This voltage coil has many turns and is arranged to be as highly inductive as possible. In other words, the voltage coil produces a high ratio of inductance to resistance. This causes the current, and therefore the flux, to lag the supply voltage by nearly090. An adjustable copper shading rings are provided on the central limb of the shunt magnet to make the phase angle displacement between magnetic field set up by shunt magnet and supply voltage is approximately090. The copper shading bands are also called the power factor compensator or compensating loop. The series electromagnet is energized by a coil, known as “current” coil which is connected in series with the load so that it carry the load current. The flux produced by this magnet is proportional to, and in phase with the load current.
• Moving system: The moving system essentially consists of a light rotating aluminium disk mounted on a vertical spindle or shaft. The shaft that supports the aluminium disk is connected by a gear arrangement to the clock mechanism on the front of the meter to provide information that consumed energy by the load. The time varying (sinusoidal) fluxes produced by shunt and series magnet induce eddy currents in the aluminium disc. The interaction between these two magnetic fields and eddy currents set up a driving torque in the disc. The number of rotations of the disk is therefore proportional to the energy consumed by the load in a certain time interval and is commonly measured in killowatt-hours (Kwh).
• Braking system: Damping of the disk is provided by a small permanent magnet, located diametrically opposite to the a.c magnets. The disk passes between the magnet gaps. The movement of rotating disc through the magnetic field crossing the air gap sets up eddy currents in the disc that reacts with the magnetic field and exerts a braking torque. By changing the position of the brake magnet or diverting some of the flux there form, the speed of the rotating disc can be controlled.
• Registering or Counting system: The registering or counting system essentially consists of gear train, driven either by worm or pinion gear on the disc shaft, which turns pointers that indicate on dials the number of times the disc has turned. The energy meter thus determines and adds together or integrates all the instantaneous power values so that total energy used over a period is thus known. Therefore, this type of meter is also called an “integrating” meter.
Basic operation
Induction instruments operate in alternating-current circuits and they are useful only when the frequency and the supply voltage are approximately constant. The most commonly used technique is the shaded pole induction watt-hour meter, shown in fig.44.1 (b).

The rotating element is an aluminium disc, and the torque is produced by the interaction of eddy currents generated in the disc with the imposed magnetic fields that are produced by the voltage and current coils of the energy meter.
Let us consider a sinusoidal flux ()tφ is acting perpendicularly to the plane of the aluminium disc, the direction of eddy current by Lenz’s law is indicated in figure Fig.44.2. It is now quite important to investigate whether any torque will develope in aluminium disc by interaction of a sinusoidally varying flux ei()tφ and the eddy currents induced by itself.0daveeeeTIIIIφφφφβ∞∠=∞�� (44.1)
where φ and eI are expressed in r.m.s and 0β�� (because the reactance of the aluminium disc is nearly equal to zero). Therefore, the interaction of a sinusoidally varying flux ()tφ and its own eddy currentei (induced) cannot produce torque any on the disc.
So in all induction instruments we have two fluxes produce by currents flowing in the windings of the instrument. These fluxes are alternating in nature and so they induce emfs in a aluminium disc or a drum provided for the purpose. These emfs in turn circulate eddy currents in the disc.
As in an energy meter instrument, we have two fluxes and two eddy currents and therefore two torques are produced by
i) are shown in fig.44.3.

()()()()()()()cos(,)cos(,)cos()cos(180)cos()cos()2coscosdavshrmsseshrmssesermsshsermsshshrmssesermsshTIIIIIIVkVkkIkZZkkVIZθααθθαθααθ⎡⎤∞Φ∠Φ−Φ∠Φ⎣⎦⎡⎤∞Φ+−Φ+−⎣⎦⎡⎤′′∞++−⎢⎥⎣⎦′⎛⎞∞⎜⎟⎝⎠ ∞ cosVIθ = power in the circuit
where ,,,,,shseshseIIVandIΦΦ are all expressed as r.m.s.

TRansformers

A transformer is a static piece of apparatus by means of which electric power in
one circuit is transformed into electric power of the same frequency in another
circuit. It can raise or lower the voltage in a circuit but with a corresponding
decrease or increase in current.

In
brief, a transformer is a device that

transfers electric power from one circiut to another.

it does so without a change of frequency.

it accomplishes this by electromagnetic induction and

where the two circuit are in mutual inductive influence of each

other.

Working of Transformer

E.M.F. Equation of a Transformer

Voltage Transformation Ratio ( K )