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I'll admit it was a hard MC, I'm hoping for around 15, worst case 13+, I doubt I went that wrong though. :cry: Averaging out from what I can see here there are definitely 3 I did wrong.

Explain why AC is preferable to DC as an input current for transformers. (2 Marks)

1. There's a cable to earth run along the very top of transmission towers. Transmission towers are also located away from any trees, this further lowers the risk of lightning strikes. Transmission towers are insulated from the lines through the use of a series of cup shaped ceramic insulators...

When you attempt to place a magnet onto a superconductor, during a superconductor's 'superconducting' state, it will set up an electrical current flow near it's surface called 'persistent currents' and will effectively operate as an electromagnet. Thus, the superconductor will expel all magnetic...

They don't contradict, both statements establish the idea that an external B field cannot penetrate that of a superconducting material. The second sentence just explains it. An external magnetic field is stopped by the superconductor as it causes currents to flow in the conductor which will...

It's fairly straight forward, p-type and n-type semiconductors have an introduced 'impurity' atom which changes their conductivity. p-type have an introduced impurity atom with one less electron (e.g. 3 valence electrons instead of 4) than that of the silicon atoms. This leaves a positive...

Yes I can help a bit, depends what the question is. @Barbernator, thanks I remember that, I forgot to mention it :) The positive momentum of the rocket is equal to negative momentum of the gases. how can mass dilate? E=Mc^2

Newton's Law of Universal Gravitation would suggest that there is a gravitational attraction between the moon and the spacecraft. Thus, using minimal energy the rocket was able to use planetary swingby around the moon, using the moons gravitational field F=MA as a force to effectively pull the...

Junction between P and N type semiconductors, is subject to high frequency light from the sun. This allows electron-hole flow across the p and n type semiconductors. Holes move to the Positive side, electrons move to the negative side. Electrons are gathered by an outer metal grid which is...

8. i don't understand why projecting 2 balls to same heights but different ranges is affected only by the initial velocity? could someone explain thanks We know that the two balls have to reach the ground at the same time when dealing with projectile motion and a constant downward uniform...

That's exactly what I believe to be correct, screw the books, I'm going with our idea. However, now I realize that over 3 sources are incorrect.

Yes 75% onward is pretty much B6. Doing Physics study for my exam, all was going well and I'm getting towards finished but there is one thing driving my CRAZY! This source says: "A typical optical fibre consists of a very pure glass core surrounded by a cladding of low refractive index."...

There's a good Train thought experiment, different to the one you asked, but it is easy to understand and is simply the observations between a man on the train and a man off the train. The man sits on a train, it is travelling at c. It travels to the right. In the train, there is: A light in...

Nevermind, worked it out.

Thread glitched..

Yeah, well now I'm not sure whether I needed to include the radius of the earth in the answer either. I just looked at a worked example of a geostat orbit at 35800km and the solution did not take into account the radius. However, on the contrary I am 99% sure that the distance was from the...

I added Earth's radius now, but I'm not sure if it's correct.

-GMm/r P.E at= 6*10^6m minus P.E at= 5*10^4m Thus: -(6.67*10^-11 x 6*10^24 x 750)/12.38*10^6 - [-(6.67*10^-11 x 6*10^24 x 750)/5.638*10^4] = -2.424*10^10 - ( -5.324*10^12) = 5.3*10^12j Can someone tell me if this is wrong or not? Not sure myself.

We'd be looking around 36,000km, so we need approx 3.6x10^7m as our answer. Using r^3/T^2 = GM/4(pi^2) r^3 = (6.672x10^-11 x 6x10^24)/4(pi^2) x 86400^2) Then cube root both sides to get r= 4.23x10^7 Take 6.38x10^6m away from the answer and you will get: 3.59x10^7m For T, I just used...

That's a pretty hard question, but I haven't revised Space yet, I do that tomorrow. I'd say that the gravitational force is inversely proportional to the distance between the planets and the sun, yet we need to also consider the mass of the planets. I'd basically say that using Newtons law of...