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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
When a Resister is jumpered out what is the voltage across the resistor?
A Resistor [note spelling] when jumpered-out has a theoretical resistance of zero. The voltage across same is zero.
To "jumper-out" is presuming a wire across the resistor: Theoretically this "ideal" wire has zero resistance, however, in practice a "thin" copper wire of (say) 10mm length - e.g., about the length of a 1/8th-watt resistor - would have a resistance around the milliohm.
Depending on the current passing through a wire (per V=IR) the voltage might be nothing or a mega-volt, as a function of the current and cross-section of the wire.
However, anything over, say, a small number of amps through a real-world "thin" wire would cause the wire to act as a fuse and break, so, in the case of a thin wire (0.25 mm say) we're looking at near zero volts across the resistor/wire combination at say 0.01 Amps and tending the supplied voltage at, say, 10 amps.
If, on the other hand, the resistor is no longer in the circuit (literally "jumpered out") then the theoretical resistance of the "gap" where the resistor should be is infinity (real-world: The order of megaohms). The makes the voltage across same just about the voltage supplied to either side of said resistor as if it were not there, which will depend on the rest of the circuit.
What material conducts sound the best?
The best type of material that conducts sound the best would be any solid. Only because of the sound that hit the compacted atoms and it would travel the fastest.
Does the outer skin of a human body has higher resistance than the inside of the human body?
no because the outer skin is dead and the inner skin is still alive and young. that is why when you scratch your skin, it turns white.
What is the difference between dry and wet corrosion?
dry corrosion is taken place in the presence of gases whereas wet corrosion takes place in the presence of moisture in air
Should you use fiber optic lighting?
Less expensive - Several miles of optical cable can be made cheaper than equivalent lengths of copper wire. This saves your provider (cable TV, Internet) and you money. Thinner - Optical fibers can be drawn to smaller diameters than copper wire. Higher carrying capacity - Because optical fibers are thinner than copper wires, more fibers can be bundled into a given-diameter cable than copper wires. This allows more phone lines to go over the same cable or more channels to come through the cable into your cable TV box. Less signal degradation - The loss of signal in optical fiber is less than in copper wire. Light signals - Unlike electrical signals in copper wires, light signals from one fiber do not interfere with those of other fibers in the same cable. This means clearer phone conversations or TV reception. Low power - Because signals in optical fibers degrade less, lower-power transmitters can be used instead of the high-voltage electrical transmitters needed for copper wires. Again, this saves your provider and you money. Digital signals - Optical fibers are ideally suited for carrying digital information, which is especially useful in computer networks. Non-flammable - Because no electricity is passed through optical fibers, there is no fire hazard. Lightweight - An optical cable weighs less than a comparable copper wire cable. Fiber-optic cables take up less space in the ground. Flexible - Because fiber optics are so flexible and can transmit and receive light, they are used in many flexible digital cameras for the following purposes:
- Medical imaging - in bronchoscopes, endoscopes, laparoscopes
- Mechanical imaging - inspecting mechanical welds in pipes and engines (in airplanes, rockets, space shuttles, cars)
- Plumbing - to inspect sewer lines
Because of these advantages, you see fiber optics in many industries, most notably telecommunications and computer networks. For example, if you telephone Europe from the United States (or vice versa) and the signal is bounced off a communications satellite, you often hear an echo on the line. But with transatlantic fiber-optic cables, you have a direct connection with no echoes.
Why less voltage drop with 240 wire vs 120 wire for the same length of run?
Voltage drop in wire is determined by the "gauge" of the wire, which is the thickness of it. A 12 gauge wire is thicker than a 14 gauge wire. The 14 gauge wire will have more voltage drop caused by the current passing through it because it is smaller and has more resistance.
Voltage drop will also be affected by the amount of voltage on a wire. It would be incorrect to assume that voltage drop is a percentage based on the length of the wire. The wire gauge affects the resistance of the wire, but assuming the same size (gauge) of wire, a higher voltage will have a greater force behind it than a lower voltage so essentially the resistance of the wire doesn't affect higher voltage as much as it does lower voltages.
If you were to compare electrical wiring with plumbing, voltage would be equivalent to water pressure, and amps would be equivalent to flow, or gallons per hour.
Additional Comments and Answer for European Electrical Installations
The questioner probably really means "Why is there less voltage drop for a cable operating at 240 V, compared to the same cable operating at 120 V".
If this is the case, then the answer is simple. For a load of any given power, the higher the voltage, the lower the resulting current. For example, let's suppose we have a 1000-W load operating at 230 V -this load will draw a current of 4.35 A. The same load operating a 120 V will draw a current of 8.33 A. So, for any given conductor size, the voltage drop (Iload x Rconductor) will clearly be greater.
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As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.
Before you do any work yourself,
on electrical circuits, equipment or appliances,
always use a test meter to ensure the circuit is, in fact, de-energized.
IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
What is a silicon-controlled rectifier?
A silicon-controlled rectifier is a semiconductor device that is used as a switch in an electrical circuit. It's a solid state direct current (DC) electronic switch. There is a ton of information including a detailed description of the SCR and a list of applications at the Wikipedia article. A link is posted below.
Yes, the total current delivered to multiple devices in parallel is the sum of the individual branch currents (the vector sum if there is inductive load).
Circuit breakers are resettable automatic switches that help protect against circuit overload (such as running too many hair driers and heaters on at one time) and faults (such as dropping the hair drier into a bathtub). Circuit breakers "operate" (or open) to stop current flow to the fault or overloaded circuit.
Does voltage flow across a circuit or is it impressed across a circuit?
Voltage is impressed across a circuit. Current flows through a circuit.
How commutator converts AC to DC?
There is no conversion of AC to DC a commutator is the key to creating straight DC voltage. "The commutator rotates with the loop of wire just as the slip rings do with the rotor of an AC generator. Each half of the commutator ring is called a commutator segment and is insulated from the other half. Each end of the rotating loop of wire is connected to a commutator segment. Two carbon brushes connected to the outside circuit rest against the rotating commutator. One brush conducts the current out of the generator, and the other brush feeds it in. The commutator is designed so that, no matter how the current in the loop alternates, the commutator segment containing the outward-going current is always against the "out" brush at the proper time. The armature in a large DC generator has many coils of wire and commutator segments. Because of the commutator, engineers have found it necessary to have the armature serve as the rotor(the rotating part of an apparatus) and the field structure as the stator (a stationary portion enclosing rotating parts). Which is the inverse of an AC Generator."
Why conductors are designed using smaller strands?
Two reasons:
- Mostly a stranded wire is far more flexible than a solid one and less likely to break after repeated flexing.
- At AC frequencies in the RF range an effect called the "skin effect" starts to become significant, current flow restricts itself to the skin of the conductor and the wire resistance rises. Stranded wire offers more skin and thus reduces the wire resistance again.
Why do you need varnish in transformers?
A: The iron on a typical transformer is made up by adding iron leaves to the core. These leaves will vibrate if held loosely by a screw which add to eddy current. to stop the vibration varnish is applied to keep the leaves of iron coherent
The AC voltage is in the form of a sine wave. Half the wave is above zero volts and half below. In half wave rectification the bottom half of the wave is chopped off. That leaves a series of "humps' interspersed with a half wave time of zero voltage. The capacitor stores charge that decays through the resistor. The more capacitance the longer the charge is held and the voltage smooths out somewhat to approximate a DC voltage with some ripple. A full wave rectifier flips the bottom half of the waveform above zero so that the period of time the voltage is close to zero is reduced and the less ripple in the output voltage and the capacitor will smooth out the voltage even more.
What do the coloured bands of the resistors mean?
They are a standard code with each individual colour representing a single whole number (1-10) indicating the resistance or ohm value.
Additionally the gold band represents 5% "tolerance" and the resistance value is more precise. The silver banded resistors have only 10% tolerance & therefore are not as precise in ohm value. Such should be cheaper to buy than the gold ones.
Why is electrostatic discharge a problem for MOSFET and what occurs?
It can punch through the thin insulating oxide layer between the metal gate and the semiconductor channel, causing them to short and destroying the field effect transistor. For some transistors a discharge of as little as 20V (which you could never feel) would be adequate to do this.
What is even worse is a partial punch through, which does not immediately destroy the field effect transistor. Instead it degrades it causing it to unexpectedly fail a year or more later. These can cause unacceptable levels of warranty returns and/or customer complaints.
A yagi is a directional antenna consisting of two or more dipoles.
What is bootstrap sweep circuit?
A bootstrap sweep circuit is a connection between two machines that can be used by themselves. It would be like linking a computer to a printer without Internet capabilities. The printer can work without the Internet on its own and so can the computer.
A 'collapsing circuit' - in its idea - is a circuit designed to detect a failure in a circuit and act on it. The most basic implementation would be to monitor voltage/amperage levels on the target circuit and react when those levels change (a wire is cut, an element wears out etc.).
Collapsing circuits are used in electronic security devices like alarms (alarm is set off if tampering in the device is detected), and bombs (the load is detonated when, for example, the counter is disconnected).
Typical (generic) usage for such circuits is mainly intrusion detection and failover systems - a collapsing circuit could be used to warn the user of a failure, or to enable a backup system.
One would do good to distinguish between physical (ie. electronical) and logical (signal-based, software) 'collapsing circuits'.
What are the differences between parallel circuit and series circuit?
Parallel circuits can have more than one way around the circuit I.e.
______O______
|______O_____|
|_____|-______|
Series circuits only have one way around the circuit I.e.
______O______
|______|-_____|
Key:
__ or | = wire
O = light
|- = battery/cell
Baud rate is the number of samples per second. Data transfer rate is the number of bits per second. Since the analog phone line can have more than two values at any one sample, this translates to more bits per second than baud.
There is a tendency to confuse baud rate with data rate. The two terms are not always the same.
