Questions tagged [theory]

Theory is a contemplative and rational type of abstract or generalizing thinking, or the results of such thinking. Depending on the context

Theory is a contemplative and rational type of abstract or generalizing thinking, or the results of such thinking. Depending on the context, the results might for example include generalized explanations of how nature works. The word has its roots in ancient Greek, but in modern use it has taken on several different related meanings. A theory is not the same as a hypothesis. A theory provides an explanatory framework for some observation, and from the assumptions of the explanation follows a number of possible hypotheses that can be tested in order to provide support for, or challenge, the theory.

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Ceramic caps vs electrolytic. What are the tangible differences in use?

A quick google around and all I seem to be able to find are people talking about the physics & the chemistry of the capacitors but not how this affects choosing which to use. Avoiding talking about the difference in their make-up, and the larger…
James T
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Noise and what does V/√Hz actually mean?

Noise figures in (op-amp) datasheets are expressed in V/√Hz, but Where does this unit come from? Why the square root? How should I pronounce it? How should I interpret it? I know lower is better, but will a noise figure that doubles also double the…
jippie
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Is there a dual of the transformer?

Capacitors and inductors are duals of each other . A transformer is made of two inductors, and transfers power through mutual inductance , through the magnetic near-field (right?) Also, you can vary the ratio of voltages or currents by changing the…
endolith
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Why do microcontrollers have so little RAM?

Maybe this is more of a perceptional problem, but it seems like microcontrollers have advanced by leaps and bounds in the last 20 years, in almost all regards, higher clock speed, more peripherals, easier debugging, 32-bit cores, etc... It is still…
Grady Player
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When people talk about a device "drawing" current, what do they mean? Why do devices under load "draw" more current?

In my (extremely rudimentary) understanding, the amount of current flowing in a circuit is determined by a) its resistance, and b) the voltage of the power source (voltage from beginning to end), which forces the charge to flow through. Why then, do…
Chris Cooper
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Where does U for voltage come from?

I believe in Europe the letter U is commonly used for voltage in (eg.) Ohm's law \$U = I × R \$. I think I understand where the letter V came from, commonly used in North America. But what's the story with U?
jippie
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Why is the Nyquist data rate lower than the Shannon data rate?

In the book Computer Networks , the author talks about the maximum data rate of a channel. He presents the Nyquist formula : C = 2H log\$_2\$ V (bits/sec) And gives an example for a telephone line : a noiseless 3-kHz channel cannot transmit binary…
subb
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Why does QAM use a grid-like distribution versus a more efficient spacing?

"Stand-Up Maths" recently did a video about QAM/data encoding. He presented a diagram of the encoding spacing for QAM: I'm from a software engineering background and I couldn't help but think: given that telecommunication companies are always aiming…
Joshua Walker
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Do electrical devices "take what they need"

One concept of electronics I have a hard time understanding is if things like motors, actuators, solenoids etc. use as much power as they need or what you give them. If a motor needs 12 volts and 500ma and I supply it with 12 volts and 3000ma will…
G Thompson
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In theory, is it possible to make a logic gate that uses zero current?

CMOS greatly reduces the current draw of ICs because one of the complementary FETs is always in the non-conducting mode, so there is only a flow of current during the transition between states, which is just the amount of charge on the gate's…
endolith
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How many transistors at minimum do you need to build a general-purpose computer?

I'm wondering what the simplest design for a general-purpose (Turing complete) computer is. To my surprise, I haven't found much on the web. Surely this is a known problem?
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Why isn't a transformer a short circuit?

I'm a newbie with electronic components and I never fully understood why transformers , while essentially being a short-circuit from a wire perspective, don't act like short circuits (i.e. they don't just blindly behave like a waterfall of…
user3834459
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Are E and B fields in phase in electromagnetic radiation?

I recently wrote this answer , in which I said: Radio waves are electromagnetic radiation . Electromagnetic radiation contains of two components, one electrical and one magnetic. These components create each other, as said above. The red magnetic…
user17592
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RC differentiator circuit explaination

This is the circuit of a basic RC differentiator, with the input/output voltage waveforms. First of all, I don't understand why there is decrease in the output voltage (discharging of charge from capacitor) as long as the supply is still on.…
Nishu
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Can an electric circuit do recursion?

Can an electric circuit do recursion? By recursion I mean any kind of recursion, tail, binary, nested, etc: http://www.sparknotes.com/cs/recursion/whatisrecursion/section2.rhtml By electric circuit I mean a simple board without any special chips,…
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