Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [physics]

Physics is the natural science that involves the study of matter and its motion through space and time.

Generically, Physics is the natural science that involves the study of matter and its motion through space and time, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.

On Electrical Engineering point of view, it is related to all subjects connect to the pysic property of the components and circuits, such as semi-conductor theory and/or behavior. Also, it is related to physics interaction components, like , , , and others.

To general Physics question, consider consulting Stack Exchange - Physics.

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What limits CPU speed?

I've recently talked with a friend about LaTeX compilation. LaTeX can use only one core to compile. So for the speed of LaTeX compiliation, the clock speed of the CPU is most important (see Tips for choosing hardware for best LaTeX compile…
Martin Thoma
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How do I prove to my physics teacher that adding a battery in parallel doesn't double the current?

simulate this circuit – Schematic created using CircuitLab My physics teacher said that the current through the resistor is 4A because each battery has a current of 2A if hooked up to the resistor on its own, and so they both have 2A of current…
Student
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MOSFET: Why the drain and source are different?

Why the drain the source terminal of the MOSFET function differently while their physical structure is similar/symmetrical ? This is a MOSFET: You can see that the drain and source are similar. So why do I need to connect one of them to VCC and the…
Dor
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How fast does electricity flow?

I get confused on the low-level physics of electricity from time to time. It came up in "Which way does electricity power a circuit," and I don't totally get it. How fast does electricity flow? Is the speed of an electron different in say a resistor…
travisbartley
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What is the difference between emitter and collector for BJTs?

the (surely simplistic) model of a bipolar junction transistor one is taught in foundational physics course appears to be symmetric. - So, what is the difference between the collector and the emitter of a real BJT? If the transistor were symmetric…
ARF
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Why are electrons not pushed out from the conductor at an open circuit under the influence of a power source?

Frequently, electric current is compared with water flow. For example, if I make a hole in a water tank, water will flow till the tank pressure and the atmospheric not become equal or the tank becomes empty. Why does this not happen with…
user3131972
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How do BJT transistors work in a saturated state?

This is what I know about NPN BJTs (Bipolar Junction Transistors): The Base-Emitter current is amplified HFE times at Collector-Emitter, so that Ice = Ibe * HFE Vbe is the voltage between Base-Emitter, and, like any diode, is usually around 0,65V.…
Denilson Sá Maia
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Why is there no rolling shutter when using a mechanical shutter?

So I know it might not be the best place to ask this question, but maybe some of you are familiar with the mechanics of digital mirrorless cameras and the technology of CMOS sensors. I don't quite understand why electronic image sensors, that create…
Thomas D.
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How does a nine volt battery make a spark?

With a nine volt battery, touching the two terminals together (or using a faulty terminal) will cause a spark roughly where I would want it to be. How is this possible? Is it ionizing only a very small portion of air surrounding the wires when this…
Hobbyist
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Physics behind signal reflections and series termination

I have been looking for cause of signal reflections in transmission lines. Everywhere it is concluded that the reason is impedance mismatch. I can understand if the impedance changes in the path of the signal travels, then reflection will occur, but…
Vignesh C
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Why the prevelance of mechanical oscillators in electronic circuits?

The clock sources in modern electronics seem to come invariably from quartz and MEMS oscillators, both of which generate vibrations mechanically. The amplitude and frequency of the vibration are orders of magnitudes different from the everday…
Gus
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Why does the thickness of a wire affect resistance?

A teacher explained why by using a highway analogy. The more lanes you have, the faster the cars go through, where the number of lanes obviously represent the wire thickness and the cars represent electrons. Easy enough. But after a certain point…
user27379
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Why does capacitance value changes with applied voltage?

I searched many forums and papers on google and haven't came up with anything. Even asked my teachs and they did not know. One said something about piezo effect but she was not sure about it. So here is a graph by a vendor, change of capacitance…
Alper91
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Which everyday components involve flows of charge that are not electrons?

I like this explanation of why there's nothing wrong with conventional current being the opposite direction from electron current. It mentions batteries and fluorescent bulbs as two cases where the current is not a flow of electrons. (As well as…
endolith
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Why doesn't higher frequency mean higher data rate?

My question is very primitive :) I've read multiple articles today and answers here, on Stack Exchange, but still don't understand one thing. Why doesn't frequency itself affect data rate in mobile networks? 3G/4G networks use QAM modulation, that…
Raiker
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