Recent content by CheyenneXia

You are right. The cross area at left is not twice of the right after rotating. It is not the real design. I just use this drawing for my questions. I went back to the book and the internet. I only got the info that Biot-Savart works for magnetostatic case. Other than that, not much. Do not...

Transformer equivalent circuit shows that excitation current is just a tiny friction of the primary current. I always thought the pricinple of transformer was like this: voltage on the primary winding generates the current there, then flux in the core, then voltage on the secondary winding and...

Jim you are absolutely right. I went to the lab with my colleague and found out that it was tested at 1000Hz and I used magnetostatic solver! Sadly the result doesn't change that much from 1000Hz to 10Hz or 5Hz. And we cannot find the cable to connect the LCR meter to scope. I think the...

recently I am working on magnetic solenoid and got a question. The attachment shows the simple cross-section. Blue green represents the steel providing the magnetic flux path and red is the copper wire with current flowing into the screen. Also, the whole structure is in cylindrical shape...

The reason why I ased here is because I have no clue how LCR meter excites the inductor. Thank you.

I am more and more confused. I guess I should get a book related to electronic materials and read some charpters on conductor. Thanks.

Thank you. I know why I was confused. Surface current density exists but no surface time-varying field densities. Time varying field exisits in 3D. As for your post about skin effect, I do not really get your question. Sorry.

I helped my colleagues simulate inductance of vr crank sensor in Maxwell but my simulation result is quite different compared to the test one. Our sensor is quite simple, just a piece of permenant magnet, a piece of flux concentrator made of normal steel, and one copper coil hooked outside of...

Hey many thanks for your answer and it reminds me the model of transmission line. It is clear for me now.

I went through the book of engineering electromagnetics and I have several questions I don't understand. 1. If the line integral of electrical field is not zero at the existence of changing magnetic field, then how can KVL holds with AC current flowing in the circuit? I do not know what's...

I am sorry if I sound rude. The question I was being asked was "since you do not know the frequency microwave oven operates, now tell me how you can find it out". I did googled the question but not in English and the answer got was related to water. When I said I had already googled, what...

I did. Most explanations said that it was because that frequency water molecules resanant. I think what they wanted to test me is that whether I understand EM heating. So what is your answer?

I c. Thanks. I should have thought of it at that time.

They invited me for the onsite interview though I wasnt able to answer that question. I want to know also because of my curiosity. I asked people from my lab. And my friends told me that I should tell them, ask GOD for the answer if you are not allow to use the measurement tools.

I had a phone interview. People asked me how to get the frequency of microwave oven if I do not know. I said measure it. They said, you are not allowed to use any measurement tools. Then I said, read product spec. They said, no, you do not have the spec. Finally I said I do not know. I think...