Physics Exam Thoughts (3 Viewers)

[pikachu975]

For the maglev train superconductors one what'd people write

 

[blinkandyoullmissit]

For the maglev train superconductors one what'd people write

I said superconductors are used in them for electricity distribution to power electromagnets.

* No power requirement except for cooling

* High current capability

 

[NinjaDatHSC]

i wrote it could carry large currents cause no resistance below critical temp and it is cheaper to run than conventional electromagnets cause no resistance meant not as much energy loss due to heat maybe that's the same point tho

 

[camstu]

Idk if it will let me say the site name on this without getting banned. It's just in hsc exam discussion 2017 for another site if you look for it you'll find it

found it thanks, according to that I got 17/20 in MC, not great but seems everyone had their problems in it so its ok i guess

 

[blinkandyoullmissit]

i wrote it could carry large currents cause no resistance below critical temp and it is cheaper to run than conventional electromagnets cause no resistance meant not as much energy loss due to heat maybe that's the same point tho

They don't use the meissner effect to levitate the train

 

[NinjaDatHSC]

Yeah i didn't say that in my answer. But to levitate it, don't they use repulsion by using the same pole on the train and on the tracks?

 

[ChasingMedForLife]

seems about right

 

[blinkandyoullmissit]

Yeah i didn't say that in my answer. But to levitate it, don't they use repulsion by using the same pole on the train and on the tracks?

yeah with rapidly changing electromagnets.

like positive pole on the train, positive behind the train (repulsion) then negative infront (attraction) to make it efficient

 

[Qw0pper0]

Overall velocity was 10, so Ux was 10Cos60 which was about 8.66

Doesn't Cos60 = 1/2 so it was 5m/s?

 

[janzrn]

The radiation question was bs had no clue what I was writing
Proton I half bsed it but hopefully my north west helical shape was right

To the person above, range was found using delta y = 0, finding t and subbing back into delta x.

Pre sure from the top, the proton is moving in a parabola instead of north west

 

[pikachu975]

Doesn't Cos60 = 1/2 so it was 5m/s?

They meant final answer was 8.66

 

[EngineeringHelp]

Anyone else do Medical Physics?

 

[blinkandyoullmissit]

Doesn't Cos60 = 1/2 so it was 5m/s?

Oh sorry yeah it it

 

[blinkandyoullmissit]

Anyone else do Medical Physics?

Yeah i thought it was pretty good actually

 

[Asylum99]

Anyone know what the band 5 cut off will be? Asking for a friend

 

[EngineeringHelp]

Yeah i thought it was pretty good actually

Why are different frequencies used for Sector (3.5MHz) and B (20MHz) scans?

Also, the polarity of P and Q? I got P as positive and Q as negative? Correct or nah?

 

[pikachu975]

Why are different frequencies used for Sector (3.5MHz) and B (20MHz) scans?

Also, the polarity of P and Q? I got P as positive and Q as negative? Correct or nah?

I put that too but P is negative turns out since it said "circuit" hence positive charges come out of the positive terminal. If it was just a wire it'd be P but nah

 

[fluffchuck]

Why are different frequencies used for Sector (3.5MHz) and B (20MHz) scans?

Also, the polarity of P and Q? I got P as positive and Q as negative? Correct or nah?

I don't completely remember what P and Q were, but the current travels in a clockwise direction.

 

[pikachu975]

I don't completely remember what P and Q were, but the current travels in a clockwise direction.

Yeah I thought it was a normal wire so positive charges build up at P but guess it's a circuit so positive charges go to negative (P).

 

[blinkandyoullmissit]

Why are different frequencies used for Sector (3.5MHz) and B (20MHz) scans?

Also, the polarity of P and Q? I got P as positive and Q as negative? Correct or nah?

3.5 is used cause it has less interaction with bodily tissue so is used as sector scans imaging e.g. Babies in a mothers womb. Lower energy sound waves interact less with tissue so can "reach" further into the body, but as a result has lower resolution.

20 is used in situations where less penetration is required eg eye scans or other small areas of the body. The higher energy sound waves interact more and thus give a higher resolution image. B (brightness) indicates the size/thickness of a particular layer.