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Showing posts from December, 2013

What is the difference between magneto and a.c generator?what is meant by frequency of alterneting current?

A magneto is an electrical generator that uses permanent magnets to produce periodic pulses of alternating current.

Hand-cranked magneto generators were used to provide ringing current in early telephone systems.
Magnetos adapted to produce pulses of high voltage are used in the ignition systems of some gasoline-powered internal combustion engines to provide power to the spark plugs. Use of magnetos for ignition is limited mainly to engines where there is no low-voltage electrical system available, such as lawnmowers and chainsaws. Magnetos have traditionally been used in aviation piston engines even though a low-voltage electrical system is usually available, to keep the ignition system independent of the battery and charging system and to keep the engine running in the event of alternator or battery failure. For redundancy purposes, virtually all piston engine aircraft are fitted with two magneto systems, each supplying power to one of two spark plugs in each cylinder.

Magnetos were ra…

Electric Power Transmission (College Level )

The electrical power generated in a power station situated in a remote place is transmitted to different regions for domestic and industrial uses. Here we discuss the electric power grid, power generation, transmission, and distribution.Power GridWhat is a power grid?
The power grid forms a bridge between electrical suppliers and consumers through interconnected networks.
The electrical power grid consists of three main parts:
Generating plant for electric power.Transmission of the electric power.Distribution of the electric power. Electrical Power Generation in Power StationsNormally, electric power generating plants are located near the source of power generation like dams, coal mines, etc. They may be in remote locations, and the generated power has to be supplied to the consumer in the city.
Sources for Power Generation:
The following types of resources are available for generating electrical energy for distribution:
Steam Power Plants Looking For Used Processing Plants? Find Them…

Wave Nature of Particle - the de Broglie Hypothesis( College Level)

In experiments like photoelectric effect and Compton effect, radiation behaves like particles. de Broglie, a french physicist asked whether in some situations, the reverse could be true, i.e., would objects which are generally regarded as particles (e.g. electrons) behave like waves ? In 1924 de Broglie postulated that we can associate a wave with every material object. In analogy with photons, he proposed that the wavelength associated with such a matter wave is related to the particle momentum through the relationship

where is the Planck's constant

Wavelike behaviour of a macroscopic object is difficult to detect as the wavelength is very small.
However, wave nature of particles may be detected in diffraction experiments where the dimensions of the obstacles are comparable with the wavelength of matter wave incident on the obstacle.

Example :Electron Diffraction from a Crystal

Consider a beam of electron with a speed m/s corresponding to a wavelength nm. Such a wave may be di…

Uses of DC Load line

The below figure shows the output characteristic curves for the transistor in CE mode. The DC load line is drawn on the output characteristic curves. 

Load line To draw load line, we have to find saturation current and the cutoff voltage. After plotting these values on the vertical and the horizontal axes, a line is drawn joining these two points, which represents DC load line. It represents all possible combinations of the collector current Ic and the collector voltage Vc (or Vce) for the given load resistorRc. 

Saturation point The point at which the load line intersects the characteristic curve near the collector current axis is referred to as the saturation point. At this point of time, the current through the transistor is maximum and the voltage across collector is minimum for a given value of load. Therefore saturation current for the fixed bias circuit, Ic (sat) =Vcc/Rc 

Cutoff point The point where the load line intersects the cutoff region of the collector curves is referred a…

Basic Unit Conversions

Ans:In the field of science, the metric system is used in performing measurements. The metric system is actually easier to use than the English system, as you will see shortly. The metric system uses prefixes to indicate the magnitude of a measured quantity. The prefix itself gives the conversion factor. You should memorize some of the common prefixes, as you will be using them on a regular basis. Common prefixes are shown below:
Metric - Metric ConversionsSuppose you wanted to convert the mass of a 250 mg aspirin tablet to grams. Start with what you know and let the conversion factor units decide how to set up the problem. If a unit to be converted is in the numerator, that unit must be in the denominator of the conversion factor in order for it to cancel.

Notice how the units cancel to give grams. I've shown the conversion factor numerator as 1 x 10…