i want to make a working project showing bthe working of transformer...hlp me[/b][/font]

guest.......I want a seminar project of physics of class 12

(25-12-2012, 01:10 PM)Guest Wrote: i want to make a working project showing bthe working of transformer...hlp me[/b][/font]

To get full information or details of physics investigatory projects for class 12th cbse on transformer please have a look on the pages

http://slidesharetanuj187/transformers-project-report

if you again feel trouble on physics investigatory projects for class 12th cbse on transformer please reply in that page and ask specific fields in physics investigatory projects for class 12th cbse on transformer

(25-12-2012, 01:10 PM)Guest Wrote: i want to make a working project showing bthe working of transformer...hlp me[/b][/font]

Transformer

A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. Electromagnetic induction produces an electromotive force within a conductor which is exposed to time varying magnetic fields. Transformers are used to increase or decrease the alternating voltages in electric power applications.
A varying current in the transformer's primary winding creates a varying magnetic flux in the transformer core and a varying field impinging on the transformer's secondary winding. This varying magnetic field at the secondary winding induces a varying electromotive force (EMF) or voltage in the secondary winding due to electromagnetic induction. Making use of Faraday's Law (discovered in 1831) in conjunction with high magnetic permeability core properties, transformers can be designed to efficiently change AC voltages from one voltage level to another within power networks.
Since the invention of the first constant potential transformer in 1885, transformers have become essential for the transmission, distribution, and utilization of alternating current electrical energy.[3] A wide range of transformer designs is encountered in electronic and electric power applications. Transformers range in size from RF transformers less than a cubic centimeter in volume to units interconnecting the power grid weighing hundreds of tons.

Physics Investigatory Project Topic:-Selective Isolation and Manipulation

Abstract
The Objective : The goal of this project is to determine a general set of parameters for moving, manipulating, and cutting single-walled carbon nanotubes with and without a charged tip that can be used on a world-wide scale as a standard for nanochip fabricators.

Methods/Materials
- Pacific Nanotechnology Atomic Force Microscope

- Pacific Nanotechnology Standard AFM tip and Charged AFM tip

- Dell 2350 computer

- Silicon dioxide plated chip with electrodes and nanotube growth (94-S)

1.Obtain a sample with abundant carbon nanotube growth (AKB 94-S )

2.Place sample onto puck and into AFM (Pacific Nanotechnology), calibrate, and image a particular tube.

3.Open the LPM software (Pacific Nanotechnology) and collect image from AFM, enter scan settings and start lithography.

4.Verify cut using the AFM data.

Results
It was practically impossible to consistently move around SW CNT's.

This can be explained by the complex nature of both Columbic and Van der Waals forces acting on the nanotubes and the AFM tip acting on an atomic level.

However, efficient parameters were established for cutting tubes at different scan rates, set points, and tip voltages. With no tip voltage, a quadratic relation was discovered between the scan rate and set point. With tip voltage, a direct relation was observed.

Conclusions/Discussion
It was observed that SW carbon nanotubes were cut by an uncharged AFM tip at a lower set point voltage when the scan rate was small, around 4 μm/s. As the scan rate increased, the required set point also increase, as expected because a larger force would have to be present to cut the tube originating from the moving AFM tip.

However, an interesting outcome that was overlooked in the begging was discovered; as the scan rate becomes very small, below 4 μm/s, the required set point voltage to cut the nanotube increases. This can be explained by the fact that very slow scan rates will tend to 'push' the tube rather than cut it, as well as the friction and stickiness of the tube.

This project provides a general set of parameters for moving, manipulating, and cutting SW CNTs with and without a charged tip that can be used on a world-wide scale as a standard for nanochip fabricators.

Transformer

Definition of Transformer

A transformer is a static machine used for transforming power from one circuit to another without changing frequency. This is a very basic definition of transformer. Since there is no rotating or moving part so transformer is a static device. Transformer operates on ac supply. Transformer works on the principle of mutual induction.
History of Transformer

If we want to know the history of transformer we have go back long in the 1880s. Around 50 years before that in 1830 property of induction which is the working principle of transformer was discovered. Later the transformer design was improved resulting in more efficiency and lesser size. Gradually the large capacity of transformers in the range of several KVA, MVA came into existence. In the year 1950, 400KV electrical power transformer was introduced in high voltage electrical power system. In the early 1970s, unit rating as large as 1100 MVA was produced and 800KV and even higher KV class transformers were manufactured in year of 1980.





Use of Power Transformer

Generation of electrical power in low voltage level is very much cost effective. Theoretically, this low voltage level power can be transmitted to the receiving end. This low voltage power if transmitted results in greater line current which indeed causes more line lossesBut if the voltage level of a power is increased, the current of the power is reduced which causes reduction in ohmic or I2R losses in the system, reduction in cross sectional area of the conductor i.e. reduction in capital cost of the system and it also improves the voltage regulation of the system. Because of these, low level power must be stepped up for efficient electrical power transmission. This is done by step up transformer at the sending side of the power system network. As this high voltage power may not be distributed to the consumers directly, this must be stepped down to the desired level at the receiving end with the help of step down transformer. Electrical power transformer thus plays a vital role in power transmission.