Electronics Engineering

All test equipment has to be calibrated. It is calibrated when it comes from the manufacturer but depending on how much the test equipment is used recalibration is usually recommended.

In order to determine what size of resistor is required to operate an LED from a 9V battery, first start by knowing the current and voltage required for the LED. That information is available in the LED's specifications.

For discussion purposes, lets assume a typical LED at 2.5V and 50mW. The translates to a forward current of 20mA.

Build a simple series circuit containing a 9V battery, a resistor of an as yet unknown value, and the LED.

By Kirchoff's current law, the current in the LED is the same as the current in the resistor, which is also the same as the current in the battery. This is 20ma.

By Kirchoff's voltage law, the voltage across the LED plus the voltage across the resistor equals the voltage across the battery. This is 6.5V. (9 - 2.5)

By Ohm's law, resistance is voltage divided by current, so the resistor is 6.5 / 0.02, or 325 Ohms. The nearest standard value to that is 330 Ohms.

Cross check the power through the resistor. Power is voltage times current, or 6.5V times 0.02A, or 0.13W. A half watt resistor is more than adequate for this job.

The force that causes electrons to flow is called the Potential Difference, and it is measured in Volts(V).

It sounds like you have nickel-cadmium batteries, since 7.2 volts is an integral multiple of 1.2 volts. You should notcharge a nickel-cadmium battery with any charger that is not specifically designed for it. The issue is that overcharging these batteries will damage them, and that the battery voltage alone is not enough to determine state of charge. (You have to measure the slope of the voltage, and detect the inflection point which occurs at full charge. This is a very specific thing, so the battery must be matched to the charger.)

Sneighke answered: This discussion adds to the original question There are two types of resistance topologies: 1) Series and 2) parallel. To answer your question, resistance added in series always ADD together increasing the total resistance of the circuit. Conversely, adding parallel resistance reduces the total resistance of the circuit. So, for series circuits, R(total) = R1+R2+...Rx Parallel circuits are the exact mathematical inverse. The easiest way to determine parallel resistance is to add the inverse of resistance which is conductance, conductance being 1/r and is stated in Siemens (hold the jokes!...), then taking the inverse of the total conductance to convert back into Ohms. For example, if you have three resistors R1, R2, and R3, and they are parallel connected, the total resistance of the circuit is the inverse of the sum of conductance which would be written as 1 / (1/r1+1/r2+1/r3). By definition, conductance is the inverse of resistance. An example: Given three resistors of 5, 100, and 500 Ohms, In series, R(total) = 5+100+500 = 605 Ohms. In parallel, the total is always less than the lowest resistor: Converting to conductance (used to be called Mhos which is "Ohm" backwards, but has been replaced with the SI unit of Siemens): 5, 100, and 500 Ohms = 1/5+1/100+1/500 = 0.200+0.010+0.002 = 0.212 Siemens. Converting back into resistance, 1/conductance = 1/0.212 Siemens = 4.717 Ohms which as stated above, is less than the lowest resistance resistor. In fact, sometimes working with conductance is easier in series/parallel circuits and, in particular, calculating which values of resistors are required to yield a desired resistance; usually a non-standard resistance value needed for a specific purpose in a circuit. An example: Say you need a non-standard resistance of 698 Ohms. Since we know that parallel resistors create a value lower than the lowest parallel connected resistor, you would start with the next highest standard value and then add a parallel resistor to get you what you need. In this case, you would subtract the desired conductance from the starting resistor: 698 Ohms = 1/698 = 0.001427 Siemens or 1.4327 milliSiemens. If we had a standard value resistor of 750 Ohms (remember, you have to start higher): 750 Ohms = 1.3333 mS. To find the required parallel resistor to get us our 698 Ohms, subtracting the conductances 1.4327mS-1.333mS = 99.33uS (micro Siemens) [0.00009933 S]. Converting back into Ohms, 1/99.33uS = 10.07kOhms (10,070 Ohms) which is close to the standard value of 10kOhms. Doublechecking, Add the conductances: 10,000 Ohms = 100uS 750 Ohms = 1.3333mS Adding gives a total conductance of 1.4333mS. Thus the parallel equivalent = 1/Siemens = 1/0.0014333 = 697.7 Ohms which is within 0.04% of the 698 Ohms we need which is well within acceptable error and we have our 698 Ohm resistor by connecting 10,000 Ohms and 750 Ohms in parallel.

this is because the energy can still flow through the other branches.

Linear : Traversal is linear .. ex: array,linked lists,stacks,queues NoN-linear: Traversal is not linear.. ex:trees,graphs imagine the situation of searching of particular element..in above scenarious..then u will understand easily.. Linear : Traversal is linear .. ex: array,linked lists,stacks,queues NoN-linear: Traversal is not linear.. ex:trees,graphs imagine the situation of searching of particular element..in above scenarious..then u will understand easily.. Linear : Traversal is linear .. ex: array,linked lists,stacks,queues NoN-linear: Traversal is not linear.. ex:trees,graphs imagine the situation of searching of particular element..in above scenarious..then u will understand easily..

If you are speaking of the radio amplifier, it takes the low powered signals from the radio and increases them for output to the speakers. Amplifiers usually have some provision or internal programming for splitting the signal so lower frequencies go to subwoofer and midbass speakers while higher frequencies go to tweeters.

The copper losses, because they vary as the square of the secondary/primary currents.

As the frequency becomes higher then its wavelength would decrease.

In case of mechanical waves such as sound waves higher frequency means higher the pitch. In Sanskrit it is known as 'shruthi'. Singers would sing at different shruthi.

In case of electromagnetic wave such as light, as frequency increases the colour changes. So highest frequency in the visible region will be the violet and the lowest is the red. Also the energy of the wave photon is given by the expression E = h nu, where nu is the frequency of the wave. So higher the frequency higher the content of energy in the photon compared to the lower frequency radiation.

Only if you install separate switches for each part of the circuit. The whole point of a parallel circuit - is that both parts of the circuit are controlled by the same switch.

This might be a fundamental description of a semiconductor material.

A circuit board consists of numerous electronic components, depending on the application, these components can be in the thousands or in the ten's, therefore circuit boards vary in numerous sizes, all connected using very fine electrical connection strands.

Both, Like any other form of communication. However, all analog forms of communication/transmission will end in February of 2009. All manufactures have already changed to the digital format, therefore in a couple of months any older system will be obsolete.

Capacitor banks are used to control the power factor in a power system. By connecting suitable capacitors the power factor can be controlled / maintained at a desired level. The requirement of a capacitor changes as the load changes dynamically. The same amount of capacitors can not maintain the desired power factor all the time. To be able to connect only the required number of capacitors, multiple (bank of capacitors) capacitors are included in a system. An automatic controller senses the actual power factor and connects and disconnects the capacitors from the bank as required

Yes it can be done.

Usually, this type of diode is called zener shunt voltage regulator or shunt references; it can be a 2 or 3-terminal device.

Two terminal devices rely only on the zener b2b tunneling quantum breakdown effect for generating a fixed voltage drop.

Three terminal devices work in closed loop: you put a voltage divider at the output and feed the divided voltage to the additional "control terminal", so that a closed loop is used to compensate temperature and load variations. You can check LM4041 datasheet as an example.

R is proportional to 1/4th power of transmitted power so answer is 2

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Apparent Power=Active Power+Reactive Power

or

Active Power=VI Cos(Phase Angle)

Reactive Power=VI Sin(Phase Angle)

Apparent Power= VI

A: In a series path anything added makes current to go down assuming the source remain the same

Inductor acts like a open circuit to DC at t=0 i.e at instant of closing the switch. Because it does not allow sudden change in current. Refer v= L di/dt. As t-> infinity, inductor acts like a short circuit(if pure).

The ratio of voltage to current is called resistance.

In hydraulic terms, you can equate voltage to the difference in pressure between two points, current with the resulting flow of fluid between those points , and resistance as the opposition to that flow.

Multiplexing is the ability of a number of devices to share a transmission facility.If each device needs the facility only a fraction of time,then the sharing arrangement allows the cost of the facility to be spread over many users.

post by Mohammed Alkhattab

quote from William Stallings book