Passives Education

This calculator is useful for calculating the luminous flux for LEDs where the angle is known.

Inductors do not have a stable “resistance” as conductors do. However, there is a definite mathematical relationship between voltage and current for an inductor, as follows: You should recognize the form of this equation from the capacitor chapter. It relates one variable (in this case, inductor voltage drop) to a rate of change of another variable (in this case, inductor current). Both voltage (v) and rate of current change (di

Write an equation describing the precise mathematical relationship between electric charge (Q), capacitance (C), and voltage (V).

You might have noticed on the table for specific resistances that all figures were specified at a temperature of 20° Celsius. If you suspected that this meant specific resistance of a material may change with temperature, you were right! Resistance values for conductors at any temperature other than the standard temperature (usually specified at 20 Celsius) on the specific resistance table must be determined through yet another formula: The “alpha” (α) constant is

Define the following terms: energy, work, and power.

While Oersted’s surprising discovery of electromagnetism paved the way for more practical applications of electricity, it was Michael Faraday who gave us the key to the practical generation of electricity: electromagnetic induction. Faraday discovered that a voltage would be generated across a length of wire if that wire was exposed to a perpendicular magnetic field flux of changing intensity. An easy way to create a magnetic field of changing

Reminders When Using Ohm’s Law One of the most common mistakes made by beginning electronics students in their application of Ohm’s Laws is mixing the contexts of voltage, current, and resistance. In other words, a student might mistakenly use a value for I (current) through one resistor and the value for E (voltage) across a set of interconnected resistors, thinking that they’ll arrive at the resistance of

Inductors have the exact opposite characteristics of capacitors. Whereas capacitors store energy in an electric field (produced by the voltage between two plates), inductors store energy in a magnetic field(produced by the current through wire). Thus, while the stored energy in a capacitor tries to maintain a constant voltage across its terminals, the stored energy in an inductor tries to maintain a constant current through its windings. Because of

In very simple, qualitative terms, rate the impedance of capacitors and inductors as “seen” by low-frequency and high-frequency signals alike: Capacitor as it “appears” to a low frequency signal: (high or low) impedance? Capacitor as it “appears” to a high frequency signal: (high or low) impedance? Inductor as it “appears” to a low frequency signal: (high or low) impedance? Inductor as it “appears” to a high frequency signal: (high or

∫f(x) dx Calculus alert! Calculus is a branch of mathematics that originated with scientific questions concerning rates of change. The easiest rates of change for most people to understand are those dealing with time. For example, a student watching their savings account dwindle over time as they pay for tuition and other expenses is very concerned with rates of change (dollars per year being spent). In calculus, we have

This calculates the capacitance of a capacitor based on its charge, Q, and its voltage, V, according to the formula, C=Q/V.

“Advances are made by answering questions. Discoveries are made by questioning answers.” —Bernhard Haisch, Astrophysicist Ohm’s Law is a simple and powerful mathematical tool for helping us analyze electric circuits, but it has limitations, and we must understand these limitations in order to properly apply it to real circuits. For most conductors, resistance is a rather stable property, largely unaffected by voltage or current. For this reason, we can

We're in 7-4B. In this section, we're going to take a brief look at parallel RC circuits. In the previous section, we had looked at series RC circuits, and you'll note here on our little schematic that herein lies the difference. These two components are now in parallel. In the previous diagram they had been in series. As with series RC circuits, the techniques used with other parallel configurations

In the last section, we learned what would happen in simple resistor-only and capacitor-only AC circuits. Now we will combine the two components together in series form and investigate the effects. Series capacitor circuit: voltage lags current by 0° to 90°. Impedance Calculation The resistor will offer 5 Ω of resistance to AC current regardless of frequency, while the capacitor will offer 26.5258 Ω of reactance to AC current at 60 Hz. Because the resistor’s resistance

We're continuing in section 7.1, and we're looking at inductor types and applications. All inductors are similar in certain respects. They all possess inductances, self-induced voltages, and oppose changes in current. These are these three common characteristics of all inductors. They possess inductances, they have a self-induced voltage, and they oppose changes in current. Inductors can be classed by either fixed or adjustable. Over here, we see the schematic symbol. Here

This calculator gives the reactance and admittance of an inductor or the inductance given the reactance of an inductor

Pure resistive AC circuit: resistor voltage and current are in phase. If we were to plot the current and voltage for a very simple AC circuit consisting of a source and a resistor (figure above), it would look something like this: (figure below) Voltage and current “in phase” for resistive circuit. Because the resistor simply and directly resists the flow of current at all periods of time, the waveform for

No text on electrical metering could be called complete without a section on bridge circuits. These ingenious circuits make use of a null-balance meter to compare two voltages, just like the laboratory balance scale compares two weights and indicates when they’re equal. Unlike the “potentiometer” circuit used to simply measure an unknown voltage, bridge circuits can be used to measure all kinds of electrical values, not the least of

PARTS AND MATERIALS Two 6-volt batteries Carbon pencil “lead” for a mechanical-style pencil Potentiometer, single turn, 5 kΩ to 50 kΩ, linear taper (Radio Shack catalog # 271-1714 through 271-1716) Potentiometer, multi turn, 1 kΩ to 20 kΩ, (Radio Shack catalog # 271-342, 271-343, 900-8583, or 900-8587 through 900-8590) Potentiometers are variable voltage dividers with a shaft or slide control for setting the division ratio. They are manufactured in panel-mount as well as breadboard (printed-circuit board)

The Q, or quality, factor of a resonant circuit is a measure of the “goodness” or quality of a resonant circuit. A higher value for this figure of merit corresponds to a more narrow bandwidth, which is desirable in many applications. More formally, Q is the ratio of power stored to power dissipated in the circuit reactance and resistance, respectively: Q = Pstored/Pdissipated = I2X/I2R Q = X/R