Recent content by yykcw

What I don't understand is that, B should feel A is younger than him at any time during his return trip to earth, so if he does not stop, why at the point they met, to B, A suddenly becomes older?

Assume A and B are at rest on Earth initially. Then B travel to to one light year far away from Earth with an extremely low speed (even slower than a car). So I can assume their ages are the same after B has arrived, right? Then, B returns to Earth with an extremely fast speed (~0.9c) and A and...

When wave is reflected back means power is reflected back and not all power is consumed at the load. But I am thinking if I placed the load at the position of Vmax (of the stationary wave formed by the incident and reflected wave). Isn't that all the power will be dissipated at the load, so...

I am referring to the turn-on snubber on page 5 of the following website: http://www.engr.usask.ca/classes/EE/443/notes/Snubber_Circuits.pdf I want to ask when the switch start to turn off, isn't that there will be a reverse voltage induced in Ls? Then, the voltage across the switch has to be...

As I know, when a string of solar cells connected in series, if one of the cell is shaded, it will be reverse bias due to current mismatch and the voltage can be very high, say, 20V. But in short circuit condition, the overall voltage should be zero, if other cells are in forward bias, how can...

Good idea! But I want to involve an interaction between an app and a hardware. You triggered me to think of a smart emergency door that it will open automatically when fire is catch and it sends out signals to other smart emergency door in the building to make them all open instantly. But this...

I am an electronic and comm. engineering student, I have trouble in choosing my final year project topic. At first, I decided to build an passward/face recognition based Android app for wireless door lock/unlock system. However, this idea was banned by my supervisor because of lack of...

But isn't that those E-field outside is perpendicular to the wire? I don't understand why tangential E-field will exist outside.

For an imperfect conductor, when there is current, an electric field is set up inside the wire along the direction of the current flow, and is parallel to the wire. If this is true, then what I don't understand is boundary condition tells me the tangential E-field is always continuous, if...

In wikipedia, it said for optical fiber, a loss that takes place at discontinuities of refractive index, especially at an air-glass interface such as a fiber endface. At those interfaces, a fraction of the optical signal is reflected back toward the source. But what I learned in tranmission...

So the equation I=CdV/dt has not considered the dc leakage? the actual conduction current in the wire is=∫σEdS? How about at other frequency? Is the actual conduction current inside the wire equals to CdV/dt+∫σEdS(σ is the conductivity of the dielectric) but not just CdV/dt?

Assume a voltage source connected to a capacitor which filled with a dielectric material having non zero conductivity, then, displacement current=conduction current of the wire=CdV/dt while conduction current density of the dielectric=σE=σV/d But considering dc source, displacement...