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Electronics Engineering
Electronics Engineering is a branch of engineering that deals with practical applications of electronic components, devices, systems, or equipment. Electronics are devices that operate on low voltage sources, as in electron tubes, transistors, integrated circuits, and printed circuit boards and use electricity as part of its driving force.
24,372 Questions
How does a radio transmitter produce radio waves?
There are two primary types of electrical amplification available for any application.
The first type, transistor amplification, is what you are most likely familiar with. This is the common form of amplification used today in most consumer products like radios and car amplifiers. However, before the invention of the transistor, vacuum tubes did the same job. Tubes are electrical switches mounted inside of glass enclosures that are under vacuo. They resemble light bulbs. In radio transmission, however, these vacuum tubes are commonly the size of a household clothes dryer. These tubes amplify the frequency before the voltage is sent up the radio station's transmission tower. At the top of the tower, a broadcast antenna is mounted. These antennae are special shapes and lengths that correspond to both the frequency and direction of the intended transmission.
Why some materials obey ohm's law in terms of properties?
"Compliance" with Ohm's Law is an interesting topic. (The specific answer to the question is at the bottom of this answer, but the introductory material is essential to understanding.
In point of fact, Ohm's Law applies in every single case, every time. It simply states that voltage equals current times resistance.
The problem that many people have is one of comprehension, and the fact that no device maintains constant resistance when voltage or current changes, so it appears that Ohm's Law does not apply, when it fact it does. It is simply a matter of perspective.
Take a diode, for instance, in a forward bias condition. As you increase the current, the voltage increases, but the curve does not appear to comply with Ohm's Law. This is even more apparent with a zener diode in reverse bias condition. We say that the diode has dynamic resistance. While this is true, the greater truth is that, for any single condition of voltage, current, and resistance, Ohm's Law applies. That is the fundamental definition of resistance.
The same example can be made of an ordinary light bulb. It has a cold resistance which is vastly different than its hot resistance, but you can still use Ohm's Law to evaluate its performance in any single situation.
All of that said, to answer the question, no material purely obeys Ohm's Law. In order to "obey", the material must have a constant resistance that does not change when current or voltage changes. That is a theoretical concept that does not exist in practice.
AnswerThere seems to be a major misconception surrounding Ohm's Law. Ohm's Law simply states that 'the current flowing along a wire, at constant temperature, is directly proportional to the potential difference across its ends'.
Yet some people have 'rewritten' it, so that it reads: 'Ohm's Law states that the current flowing through a conductor is directly proportional to the potential difference and inversely proportional to resistance', or 'Ohm's Law states that current is voltage divided by resistance'. In fact, neither of these statements is true. Ohm's Law makes no direct reference to 'resistance', and does not give any formula for determining resistance!
Put simply, if the ratio of voltage to current remains constant for variations in voltage, then a conductor or device is obeying Ohm's Law. If this ratio changes for variations in voltage, then it is NOT obeying Ohm's Law. It's as simple as that!
Having said that, the ratio of voltage to current (resistance) will always tell us what the resistance of the circuit or device happens to be FOR THAT PARTICULAR RATIO.
The equation I = V/Ris not Ohm's Law formula, as many people believe. There is NO Ohm's Law 'formula'! The equation comes from the definition of an ohm, which is equivalent to a 'volt per ampere' -hence, I = V/R.
When we say "number of g forces" the g we are typically (not always) talking about is the average overall Earth of around g = 9.81 N/kg or m/sec^2 (See NOTE)
So, for example, if a jet jock pulls 2 g's in a hairy vertical climb, he's pulling 2g = 19.62 N/kg on his body. And if his mass is m = 100 kg, that means his effective weight is W = m(2g) = 1962 Newtons.
Bottom line. g forces are measured as the number of average g's.
NOTE: N/kg = kg.m/sec^2//kg = m/sec^2 which is to say they are equivalent units.
If the number of turns in the primary side of the transformer is 200 and the number of turns in the secondary coil is 100, the turns ratio is 200 to 100, or 2 to 1. This application would be a step-down transformer, reducing voltage by one half and doubling current.
If the voltage is AC a transformer could be used. If the voltage is DC calculations could be made to apply the proper size resistor to the circuit so that it has a 3.7 volt voltage drop across it.
Why we need high power to generate AM signal and low power to generate FM signal?
The reason FM has lower power and AM has higher power is because the more power that an AM signal has, the farther it will go, but FM does not work that way. AM waves can bounce off of the atmosphere, especially at night. This is the reason that you can hear AM stations from far away at night. FM, on the other hand, can't bounce. FM waves only go in a straight line from the tower and no matter how much power you transmit with, an FM wave will only go a short distance. AM Waves can travel through trees and buildings, and FM can't.
Why common emitter configuration is preferred?
Reason: The common Emitter mode has voltage and current gain better than the other two configurations(CB and CC).
i.e it has a current gain greater than that of CC mode and greater voltage gain than that of CB mode.
What is the difference between 8086 and 8088 microprocessor regarding there pin diagram?
The differences are given below:
80286
1. Low data bus width (16 bit)
2. Returning from protected mode to
real mode is hard and complicated.
3. Small RAM/Memory
80386
1. High data bus width (32 bit)
2. Easy for 80386 3. Big RAM / Memory (Real memory = 4GB and virtual memory= 64TB)
What is the basic difference between relaxation oscillator and RC oscillator?
The difference between an RC and LC is that the frequency - determining device in the RC oscillator is not a tank circuit. LC can operate with A or C biasing, while RC can only operate with A.
No, it is not expensive. In fact, it is the most cheapest way of creating electricity. If you are planning to want to have your own wind making system, I recommend you to make it by using wind power, or solar power, because it more accurate and it's cheaper than all the other ways of creating electricity.
What is the difference between pure sine wave and modified sine waves?
A pure sine wave has energy at only one frequency.
Any other wave shape has energy at other frequencies in addition to the frequency of the obvious waveshape.
If you add up enough sine waves with the right frtequencoies and amplitudes, they'll add up to form any shape
you want, even a squarewave.
How do you convert mega ohm to ohm?
Ohms are the SI unit of electrical impedance. Siemens are the unit of electrical conductance. Ohms are V/A while Siemens are A/V.
Take the reciprocal of one to get the other. 100 ohms is 1/100 or 0.01 S. 1 MS or 1,000,000 S is 0.000001 ohms, 1 micro ohm. 1 mS or 0.001 S is 1000 ohms.
What are functions of collector emitter and base of the transistor?
- emitter, emits minority carriers into the thin base material
- base, controls minority carrier current flow between the emitter and collector
- collector, collects minority carriers that have passed through the thin base material
While the emitter and collector are named for their electronic functions, the base is instead named for its structural function in the first point contact transistor: it was the bottom part of the transistor that structurally supported the other parts (thus the base). However junction transistors are usually not constructed that way, in most modern junction transistors the collector is the bottom part.
What is the Frequency of a Laser?
An electron beam has no inherent frequency.
It can be modulated by a signal that has a frequency.
The individual electrons in the beam will have a quantum frequency proportional to their energy,
However these are two different phenomena and it is not clear from your question which you are asking about.
What is the difference between oscillator and vibrators?
A violin's stings vibrate at a literally infinite number of frequencies, so that is a vibration.
Oscillations occur when vibrations, from several sources, all have the same or very, very, very similar frequencies combine and become enhanced.
What do you need to complete before the current will flow?
A circuit must have three basic components to make electricity flow.
1. Source of power or electricity.
2. Wires, switches and conductors through which the current can flow.
3. And finally a load to complete the circuit.
cause its bad,replace with higher wattage rating.too much current !!
A bandpass signal, xc(t), is a signal whose one-sided energy spectrum is both:
1) centered at a non-zero frequency, fC, and 2) does not extend in frequency to zero (DC).
The two sided transmission bandwidth of a signal is typically denoted by BT Hertz so that
the one-sided spectrum of the bandpass signal is zero except in [fC − BT /2,fC + BT /2]. This
implies that a bandpass signal satisfies the following constraint: BT /2 < fC. Fig. 1.1 shows a
typical bandpass spectrum. Since a bandpass signal, xc(t), is a physically realizable signal it is
real valued and consequently the energy spectrum will always be symmetric around f = 0. The
relative sizes of BT and fC are not important, only that the spectrum takes negligible values
around DC. In telephone modem communications this region of negligible spectral values is only
about 300Hz while in satellite communications it can be many Gigahertz.
What is the calibration of the pressure instrument?
A pressure gauge is attached to the proper fitting on a bench with valves and tubing. A known weight pressurizes a piston. That pressure goes to the gauge being calibrated and the N.B.S. certified gauge. The two are compared at several points called out in the test procedure. Adjustments are made to the mechanical linkage between the gauges internal tube and the indicator needle to make it read within an allowable percentage of deviance.
A stereo receiver uses a current of 2.2 amps from a 120 volt line?
The mathematical formula to solve this is P= I x R
In other owrds the amps x the voltage = watts.
2.2 amps x 120 volts = 264 watts
Can you have a radio signal underground?
Yes, you can however the distance that a signal may be travel depends on the power and frequency of the signal. For signals at the same power a lower frequency signal will travel further.
When current flows to all parts of a circuit the circuit is open?
No, when current flows to all parts of a circuit, the circuit is actually closed and complete. An open circuit is one where there is a break or interruption in the flow of current, preventing it from completing the full loop.
Why won't your soldering work?
A: The pad is not clean it has tarnish or wrong solder with not enough soldering flux. Finally not enough heat.
