Circuits

A battery is the device that creates a potential difference in an electric circuit. It establishes an electric field within the circuit that allows charges to move from the positive terminal to the negative terminal, creating an electrical current.

This result can be achieved through various methods. Two most common are:

The electromagnetic principle: the probed quality is converted into current quality and passed through a coil wound around a magnet. That coil is then calibrated to move proportionally to the measured quality, and it thus displaces a gauge overlayed on a scale. For obvious reasons these meters are not well suited for measuring in environments with high (electro)magnetic fields.

The thermal principle: a spiral is constructed using materials that cause the spiral to displace (unwind) due to heat when a current is applied, in proportion to that current, and in turn displaces a needle overlayed on top of a scale. The measured quality is, as above, converted into proportional current. For as well obvious reasons as above, these meters aren't very useful in extreme-temperature conditions (high or low).

Method selection is based on the environment in which the meter will be used, and the measurement accuracy required.

For completeness, pressure-reading gauges oftentimes include a membrane that displaces under pressure in order to move a gauge, but these are not commonly used in electrical circuits (membranes displacing semiconducting material are used instead, to convert pressure change to either voltage change, current change or resistance change, adequately to the requirement).

The current that flows through an unloaded voltage divider is very small, close to zero. This is because there is no load connected to the output of the divider, so there is nowhere for the current to flow. The purpose of a voltage divider is to divide the input voltage between the two resistors, not to pass current.

Thanks to the property that a conductor's resistance is influenced by temperature (mainly, it increases accordingly). This property is specifically extended in materials used to construct such diodes.

It is important to remember that silicon does not a semiconductor device make. It takes layers of semiconducting material (with the occasional isolator) and impurities specifically included into the mix to alter the device's behavior.

The slope of a voltage vs. current graph represents the resistance in the circuit. It indicates how the voltage changes with respect to the current flowing through the circuit. A steeper slope indicates higher resistance, while a shallower slope indicates lower resistance.

To measure resistance, continuity, or diode voltage drop in a de-energized component, the meter's test leads are placed in parallel with the component. This allows the meter to measure the electrical properties of the component without applying power to it.

The current in the light bulb will be greater when connected to the 200-v source compared to the 110-v circuit, assuming the resistance of the light bulb remains constant. This is because current is directly proportional to voltage in an electrical circuit according to Ohm's Law (I = V/R), so a higher voltage will result in a greater current flow through the bulb.

So far we've only seen circuits that allow a single path for electricity to flow-but it doesn't HAVE to! Here's a picture of what we call a parallel circuit. See how there's one power source and two electrical devices?Conductor wires connect the battery to each bulb independently.

Since the electricity can either go into the first bulb and light it up, or on to the next bulb and light that one . . . it does both! Some electricity flows to each bulb, distributing the power equally to both. So parallel circuits have more than one path for electricity to follow!

The total voltage across both voltage sources connected together in the first circuit is 24V. This is because the two voltage sources are connected in series, so their voltages add up to give the total voltage across both sources.

Current = voltage/resistance

If those are the only components in the circuit, then

Current = 9/12 = 0.75 Ampere = 750 mA

No, resistors are measured in ohms, not amps. Ohms represent the resistance offered by the resistor to the flow of current, whereas amps (amperes) represent the measure of current flowing through a circuit.

because there is a correlation between resistance and voltage and current.

The equation resistance = voltage divided by current shows that the higher the voltage, the bigger the resistance,, and the bigger the resistance the hotter the filament lamp will get because of the electrons bumping into each other which means there is a loss of energy and that energy is being transferred to the filament making the actual filament bulb hot since there is more thermal energy wasted at the end.

Connecting an ammeter in series with a resistor in a circuit will not affect the current through the resistor. The ammeter measures the current passing through it, so it becomes part of the circuit and simply measures the current flowing through the resistor without changing it.

Capacitors can go bad due to factors such as overheating, voltage surges, age, or excessive use. Over time, the dielectric material inside the capacitor may degrade, causing it to lose its ability to store and release electrical energy effectively.

A "thermal runaway" occurs when a transistor is heated to such a point, that the more heat it has, the quicker it will accumulate it. This usually involves leakage current which typically increases with temperature, and which causes more current to flow - which increases the heat buildup in the transistor more, and the cycle continues. This heat buildup rapidly accelerates, and it invariably and quickly (in a matter of seconds or quicker) burns out the transistor as it reaches temperatures it was not meant to safely handle.

The plates in a capacitor can be made from various conductive materials such as aluminum, ceramic, or tantalum. These materials are chosen based on factors such as cost, performance requirements, and environmental considerations.

The relationship between stimulus voltage and response amplitude on a single nerve fiber follows the all-or-nothing principle. Below a certain threshold voltage, there will be no response. Once the threshold is reached, there will be a maximal response amplitude without variation with higher stimulus voltage.

Current lags voltage in an inductive circuit. The angle by which it lags depends on

the frequency of the AC, and on the relative size of the inductance compared to the

resistance in the circuit.

In the flashing and quenching experiment, the neon bulb twinkles because the voltage across the capacitor drops below the breakdown voltage of the neon bulb. This causes the bulb to briefly turn off before the capacitor charges again and the process repeats, resulting in the twinkling effect.

The question seems to imply that ever since Creation there has always been

a grand cosmic role for the laser diode, and that once our species attained

the ability to invent it, it was then Mankind's holy mission to sally forth and

find its function.

I think it was more like: Once the purification and doping of solid-state materials

had progressed to the point where a diode could be fabricated out of a couple of

pancakes of them, AND someone over in a different lab had succeeded in getting

a laser out of a roomful of flashtubes and a piece of ruby the size of a pencil,

somebody else ... in a job where he didn't have to worry about purpose, profit,

or function but he could get paid to just come in every day and play around with

stuff, maybe at the old Bell Labs ... read about both of those, and figured out

a way to combine them, doping and joining a couple of pure stones in just

the right way that when he connected it to a battery, it would have diode

characteristics AND would lase! And then, he showed it to his boss, wrote and

published report about how he did it, built a few to demonstrate at cocktail

parties and Physics conferences, and went on to play with something else,

while we ... me and the other bottom feeders called engineers ... thought up

neat things to do with the laser diode.

We built the cool laser pointers, that you could hang on your key-chain, put

a red spot on the screen during your high school presentations, do optical

experiments with, and give your cat some great exercise chasing the red spot

on the floor. We built laser diodes and detectors to create and detect microscopic

pits on a high-polished plastic surface, small enough fit into a machine that could

fit in your backpack, run on a couple of skinny batteries, and hold a plastic disk

with an hour of music 'burned' on it. We put laser diodes and detectors into your

computer mouse, that can detect textures so tiny that you can use a sheet of

white paper for a mouse-pad, and we got rid of the clunky potentiometers and

wheels inside the mouse, that used to pick up hair and gunk and get jammed

every couple of months.

But probably the most important bright idea we had that takes advantage of the

laser diode was the method we designed to efficiently couple the light from the

diode into one end of a glass fiber ... the width of a hair and miles long ... and

detect it at the other end. From there, it was a piece o' cake to 'modulate' the

output of the diode, detect the variations at the other end, and kick off the

whole modern fiber phenomenon, that now carries trillions of bits of data

over a single fiber every second. This, at last, solved the cosmic background

requirement that lay unfulfilled since Creation, when finally, subscribers are able

to satisfy their crying need and fundamental human right to stream a different

movie into each room in the house while recording three more to watch later in

case they ever feel like it. Or to have the choice of 300 channels when they plop

down at the TV, even though there's STILL nothing on.