Electronics Engineering

A halogen lamp a uses a tungsten filament, but it is encased inside a much smaller quartz envelope. Because the envelope is so close to the filament, it would melt if it were maA halogen lamp also uses a tungsten filament, but it is encased inside a much smaller quartz envelope. Because the envelope is so close to the filament, it would melt if it were made from glass. The gas inside the envelope is also different -- it consists of a gas from the halogen group. These gases have a very interesting property: They combine with tungsten vapor. If the temperature is high enough, the halogen gas will combine with tungsten atoms as they evaporate and redeposit them on the filament. This recycling process lets the filament last a lot longer. In addition, it is now possible to run the filament hotter, meaning you get more light per unit of energy. You still get a lot of heat, though; and because the quartz envelope is so close to the filament, it is extremely hot compared to a normal light bulb. de from glass. The gas inside the envelope is also different -- it consists of a gas from the halogen group. These gases have a very interesting property: They combine with tungsten vapor. If the temperature is high enough, the halogen gas will combine with tungsten atoms as they evaporate and redeposit them on the filament. This recycling process lets the filament last a lot longer. In addition, it is now possible to run the filament hotter, meaning you get more light per unit of energy. You still get a lot of heat, though; and because the quartz envelope is so close to the filament, it is extremely hot compared to a normal light bulb.

This depends on whether the wire is copper or aluminum. In aluminum, you need to go UP one wire size to carry the same amount of electricity, because copper is a better conductor than aluminum. The normal ratings are as follows for the most common wire sizes in houses

Copper

14 gauge=15 amps

12 gauge=20 amps

10 gauge=30 amps

8 gauge= 40 amps

6 gauge= 50 amps

and so on. it goes all the way to a 2/0 which will carry 200amps

In aluminum you step up a size, as in

12 gauge= 15 amp

10 gauge=20 amps

and it would take a size 4/0 aluminum to rate at 200 amps, which is pretty much the standard household amperage requirement in most places in the US

Ideally an overload relay should be set above maximum load by some small amount, but below the capability of the electrical circuits being protected. For example, breakers in your home are designed for overload protection; typical home wiring is 14 awg - 12 awg. If you have a 14 awg wire (good for 15A), you may install a 10A breaker, but if needed could install a 15A breaker depending on codes. A 20A breaker would not provide overload protection since it is too big. It would provide fault protection.

A multivibrator produces square or rectangular waveforms.

For transmission through a radiowave.

Binary digits are represented in a variety of ways inside a computer. Random access memory (RAM) typically uses a capacitor and a transistor to represent a single bit. To set a bit, the transistor fills the capacitor with an electric charge. To clear a bit, the transistor drains the charge. The transistor can achieve this "switching" extremely quickly.

However, a capacitor cannot hold its charge for long because the transistor "leaks". In order to maintain state, memory must be constantly refreshed at regular intervals. On each refresh, if a capacitor's charge is more than half full, the transistor refills it.

The refresh rate obviously needs to be faster than the leakage rate, however the more time spent refreshing memory (the refresh overhead), the slower that memory will be because the refresh has to be interleaved into the normal memory accesses. In older DRAM, the refresh was as high 10%, but today it is less than 0.5%.

Yes. Power(P)=Current(I)xVoltage(E) or P=I x E, and since in a series circuit current is constant and voltage is additive then:

P(series)=Pr1+Pr2+Pr3........ Actually, power dissipated in series circuits is P = I^2 * R and in parallel power dissipated = V^2/R

Current flows in a circuit when there is a difference in electronic potential between two points.

You are trying to convert linear measurement to square, which is wrong. Conductivity is receprocial to resistivity; EC=1/ER the proper conversion is 1 Sm/cm=1 Ohm cm=100 Ohm m, but not Ohms per square.. Follow this link for discussion on the topic and for on-line calculators for converting electrical conductivity units. http://landviser.us/phpBB3/viewtopic.php?f=4&t=3

The microcontrollers have an 8-bit data bus. They are capable of addressing 64K of program memory and a separate 64K of data memory. The 8051 has 4K of code memory implemented as on-chip Read Only Memory (ROM). The 8051 has 128 bytes of internal Random Access Memory (RAM). The 8051 has two timer/counters, a serial port, 4 general purpose parallel input/output ports, and interrupt control logic with five sources of interrupts. Besides internal RAM, the 8051 has various Special Function Registers (SFR), which are the control and data registers for on-chip facilities. The SFRs also include the accumulator, the B register, and the Program Status Word (PSW), which contains the CPU flags. << SHARMILA TANDEL (B.E) ELECTRONICS >>

More over the rating only differs from country to country.No country employs DC current for domestic appliances because the voltage have to be stepped down or stepped up as per our requirement.

Facsimile message is the full name for what is commonly known as a fax.

It is a technique for scanning one or more sheets of paper, transmitting the images over the telephone network and printing them at a remote destination. Typically the printout is black and white and of quite limited resolution.

It was a revolutionary technology when invented. Much more accessible and versatile than teletype and virtually instant when compared to traditional postal systems. A short document can be sent between any 2 suitably equipped offices in the world within a few minutes.

With the rise in use of email and scanners fax use is declining but still has some applications as many courts give more credibility to faxed documents than email scans.

The magnetic field means there is a charge surrounding a body.

Similarly if we move so much of charge (say electrons as in electricity) we can form a magnetic field.

These electrons if provide sufficient charge around a body magnetic field can easily be developed.

what is a summing junction?

a properly designed motor wont overheat unless it is overloaded

this is something like 3/4" drill with a 1/4" shaft that is used to drill in steel

sometimes hole saws have a 1/4" mandrel that will hold the entire line of saws

the motor must be matched to the load

Most resistors are linear, or 'ohmic', devices -which means that they obey Ohm's Law. So the ratio of voltage to current remains constant for variations in voltage. In other words, their resistance remains constant -providing their power rating isn't exceeded.

So you can say that, providing the current increase doesn't cause their power rating to be exceeded, their resistance should remain the same. Resistors wouldn't be of much use if their resistance value changed whenever the current through them changed!

Wind farms are bad because it can bring down value of peoples house when tryin to sell them. Wind farms also require a huge amount of space,make a tremendous amount of noise and can kill wildlife. Such as birds of flight, they can come tumbling down with one strike of lightning hitting those blades and that would mean a lot of work. Bird in flight can also damage the turbine and thy would mean passing over lots of money.

This circuit is the vital heart of all digital electronics, computers, pulse-code telephony and so on.

A multivibrator a.k.a. flip-flop, is a device which can settle in one of two stable states. They come in various flavours, single-shot or mono-stable, bi-stable. They are the basis of counting and time-code and so on.

That requires some detective work.

If you know where it is in a circuit, you might be able to figure out its function by context (seeing what it's connected to and what it might do).

You might be able to figure out the manufacturer by looking at subtle details of the package size and shape.

If you have the equipment, there are ways to disassemble and reverse engineer the chip and see the circuitry through a microscope to figure out its internal schematic.

Normal Case:

Normally one will not find a polarity associated with a capacitor. Indeed, the quality of the manufacture would be put into question is the capacitor functions differently with different sign for the applied voltage.

Abnormal Case:

While common resistors are expected to function independent of polarity, it is possible to create resistors which are nonlinear and nonsymmetric in response to applied voltage. Just as diodes are nonsymmetric, one can imagine a diode-like material incorporated into the material of the capacity. There is no clear application for a nonsymmetric capacitor.

The only reason to label a capacitor as preferring one side positive over the other might be the effect of the rate of discharge is one of the charged surfaces is exposed to an environment which preferentially picks up or loses charge and there by affects performance.

common emitter using fixed bias

A diode is basically a PN junction device. P type semiconductors are rich in holes while N types are rich in electrons. (Rich means majority carriers here, which are found in the outer shell of atoms).

Thus at the junction of this P and N type material, electrons and holes will combine resulting in a deficiency of charge carriers. This is termed the depletion region.

When you attach the negative terminal of a battery to the N end of the diode and the positive terminal to the P end, the electrons will be repelled towards the junction and holes too will move towards the junction region, making it thin (narrow) (Further increase in voltage will make current to pass through). The opposite occurs when they are connected the other way. The region becomes thin.

For normal operations, zener diodes are connected in reverse (diodes usually are connected reversely unless you want drop some voltage) the depletion layer widens, as described above. But at a certain reverse voltage, the zener starts to conduct suddenly. This is called avalanche/breakdown voltage. How the layer becomes thin (if at all, seems improbable) when they are reverse connected, I do not know.

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