Electronics Engineering

No current flows when the the voltage is zero.

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The absolute value of -9 is

=|-9| = 9

Explanation :

Here's how you can picture absolute value: Think of a railroad track with a zero sitting in the middle of it. Every little notch to the left and right of the zero is another number. Negative numbers line up on the left; positive numbers run along the track to the right. So, the number -4.0 is 4 units away from zero. The number -45.3 is 45.3 units away from zero and the number 10 is 10 units away from zero. Therefore, the absolute value of any number is really a positive number (or zero). You identify an absolute value of a number by writing the number between two vertical bars: |number|.

Mainly there are three points,

1. If you give AC to the field coil, there is no need of rotating it, as AC itself produces alternating flux.Thus generator will give Transformer action which actually transfer the power not actually it generates or produce as per the basic law of mutual Induction.

2.In case if you rotate the field giving AC Supply by a prime mover , actually constant poles(as in physical magnet) will not be produced.For every cycle of rotation,there will be continuous change in the poles in respect to three windings of Armature.So as it results irregular waveforms of voltages,we cant tap the pure sinusoidal 3 phase supply from armature.Most probably it will get distorts & might be chances of burning of Stator(armature)coil in Alternator.

3.So to overcome come from all above disadvantages, DC excitation will be given so that constant field strength will be maintained as in case if we employ permanent magnets which produces constant flux

No corrosion is not a reaction of a metal with nitrogen in the air. Nitrogen in relatively innert and will not normally form chemical compounds. It is the Oxygen in the air that causes the corrosion.

here's a cogent discussion: http://answers.yahoo.com/question/index?qid=20090215214428AAltCZz

It measures the current.

Usually,there are many mains sockets in a flat to provide electricity for electrical appliances.Do you know how these mains sockets are connected to the electric cable that carries electricity to the flat?

The electric cable that carries electricity to a flat is connected to the consumer unit.In the consumer unit,the electric cable branches into a number of parallel circuits that deliver electricity to ceiling lamps,mains sockets,air conditioners(or other appliances with high working current),etc.The circuit that delivers electricity to main sockets exists in form of a ring and is therefore called a ring circuit.

The ring circuit provides two paths for electric current to flow from the consumer unit to the mmain sockets.Each path only carries half of the electric current.Therefore,the chance of overloading the circuit is reduced.Besides,if one of the paths is damaged,there's still another path for carrying electric current.

It depends upon the connection of the resistors, if the resistors are connected in parallel then the voltage is same where as in case of resistors connected in series the voltage is different across different resistors.

Carefully scrap the insulating material off along a straight line on the resistor body using a pen knife until you can see the spiral track of the resistive material.

Chances are you can still measure some resistance, using either end of the connection lead and a pointed pin, pricking at the spiral track.

Starts from one end and advance on each spiral track until you have found an open circuit. Record the resistance before this happens. Do the other end using the same method.

Add the resistance found in both cases and adds 10% more. This will give you the approximate resistance of the original resistor.

This method often works because resistor burns open in one spot only.

Due to inductance there is a spike in output voltage

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AC, when you're going to test a product which cannot tolerated the power source in your home. ex. in testing a 15A bulb, you cannot test it directy to the wall plug in your home instead you use AC tester(alternate current) to convert the supply to its limit or else it will fry your bulb. DC(direct current), when you're testing a high voltage product and it can tolerated the power source from your wall plug.

think of potential as pressure and current as flow. you can have pressure in a water hose with out flow. open the valve and current happens.

The difference in potential divided by the impedance is equal the current.

basim evzouki invented the thermograph

There is no "the" weather radar. Weather radars are a class of radars which can be used for gathering data on weather conditions.

refer: http://en.wikipedia.org/wiki/Weather_radar

The most commonly used weather radar at the moment is Pulse Doppler Radar. There was no 1 inventor of the PDR, so it was likely developed either by corporations or research labs. Refer to http://en.wikipedia.org/wiki/Doppler_radar#History for discussion on the origins of the more basic Doppler Radar.

There are two alternate methods depending on whether the motor is single phase or three phase. On a single phase motor, reverse either the start winding coil lead or the run winding coil lead but not both. This action will reverse the motor's rotation. On a three phase motor, interchanging any two of the three coil leads will reverse the motor's rotation.

The job of the bulb in a circuit is to convert electrical energy to light. It's called the load in the circuit.

Nowadays, you can buy DC to DC convertors that do the conversion in a single module.

A cheaper solution, however, would be to use a chain of diodes - each diode will drop 0.7 volts so 4 diodes will drop 2.8 volts, reducing 12 volts to 9.2 volts.

bridge is use in 4 diode fullwave rectification to allow complete cycle so that there will an output DC for both the positive and ndgative half-cycle of the input AC.

The method of modulation has very little to do with the distance traveled, this is more dependent upon the frequency of the carrier. As the frequency gets higher the wave takes on more and more the characteristics of light. For example microwaves need to have the receiving dishes (antennae) in line of site with the transmitter.
In practical circumstances it appears the AM travels further but that is only because AM broadcasts at lower frequencies (typically 526KHz to 1625KHz) (MF) and FM at higher frequencies (typically 88MHz to 108MHz)(VHF)

p-type majority carriers are holes

n-type majority carriers are electrons

Exclusive OR gate has a variety of applications.

Even parity generator.

comparator.

encoder etc.