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AQA Physics PHYA5 - 28th June 2016 [Exam Discussion Thread]

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-thermionic emission
-magnetic lens - condenses electron been towards sample
-(sample)
-objective lens - deflects and inverts scattered electrons
-(Inverted first image)
-microscopic lens- focuses on centre of first image and inverts into high resolution final image
-(final image)

-limitations
- Thickness of the sample can cause the electron beam to slow down therefore reducing de broglie wavelength and worsening resolution
- uneven thickness of sample can cause different amounts of diffraction for electron beam therefore making the distorting final image.

(I did this mainly for my own revision... but this is pretty much all you need to learn about them)

Thanks😭

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Reply 521

C0balt

Original post by AQATrolledMe

Damn i never thought of that :tongue:

, anxiety gonna kill me, we better have something amazing to do in summer

I've got some trip plans but I'll definitely be still moaning about my results, just like last year lol. I can never distract myself enough

Reply 522

marcusman97

ASTROPHYSICS

Would it be possible for a 6 mark question on how supernovae form? Or the lifecycle of our sun?

Reply 523

veldt127

Any ideas for the 6 markers for the main paper or medical physics?

Reply 524

d14m

Why doesn't the electron simply spiral inwards to the nucleus

Reply 525

AQATrolledMe

Original post by C0balt

I've got some trip plans but I'll definitely be still moaning about my results, just like last year lol. I can never distract myself enough

well, I wish you the best of luck tomorrow :crossedf:

Reply 526

particlestudent

Original post by veldt127

Any ideas for the 6 markers for the main paper or medical physics?

Medical physics- hopefully about biopotentials, I don't think that's been a six marker since 2010 :smile:

. There's a medical thread by the way if you have questions :smile:

Reply 527

C0balt

Original post by AQATrolledMe

well, I wish you the best of luck tomorrow :crossedf:

Same to you man
I hope your username doesn't become true :tongue:

Reply 528

veldt127

Original post by particlestudent

Medical physics- hopefully about biopotentials, I don't think that's been a six marker since 2010 :smile:

. There's a medical thread by the way if you have questions :smile:

cheers

Reply 529

TajwarC

Original post by marcusman97

ASTROPHYSICS

Would it be possible for a 6 mark question on how supernovae form? Or the lifecycle of our sun?

6 marker on the lifecyle of a star or formation of a red giant would be a gift. Hope something like this comes up

Reply 530

kesh140

Anyone else doing Applied physics? Any tips?

Reply 531

arrow_h

Original post by TajwarC

6 marker on the lifecyle of a star or formation of a red giant would be a gift. Hope something like this comes up

Could you outline this for me please???

Reply 532

1017bsquad

Original post by Ainsleyy

That is literally everything you need to know about CCDs.

Heycan you help me on question 1 aii) I was thinking of using theta = R/d, with R being 1 AU and d with the distance provided, but this results in an incorrect answer, isn't that what I'm supposed to do for parallax? I really don't understand why the mark scheme used s = r*theta :frown:

Question: http://prntscr.com/blswf1
Answer:http://prntscr.com/blswku

Reply 533

marcusman97

Original post by arrow_h

Could you outline this for me please???

Is it on the spec though? Nothing has ever really appeared in past papers

Reply 534

.T.

Original post by d14m

Why doesn't the electron simply spiral inwards to the nucleus

Quantum physics, isn't necessary at all for the exam.

http://www.fnal.gov/pub/science/inquiring/questions/bob.html

Reply 535

arrow_h

Original post by marcusman97

Is it on the spec though? Nothing has ever really appeared in past papers

Not sure... this is what the spec says

Reply 536

TajwarC

Original post by arrow_h

Could you outline this for me please???

Formation:
-stars formed in gas clouds such as nebulae
-the dust particles are attracted towards eachother by gravity
-they form a clump which heats up as it gets more massive
-eventually forming a protostar
-as the core heats up, hydrogen can fuse into helium, this is when the star is a main sequence star
-the outward pressure of the large amounts of energy released by hydrogen fusion prevents the star from collapsing under its own gravity

Formation of a Red Giant
-the hydrogen in the core beings to run out. As the Hydrogen to helium core burning stops, the star expands and the outer layers (shells) cool down (this is when the star becomes red)
-the core heats up enough to allow helium to oxygen and carbon core burning.
-Hydrogen to helium shell burning occurs.
-Once the helium in the core runs out, Helium to oxygen and carbon shell burning occurs.
-In lower mass stars the core will not heat up to allow any more fusion so it contracts under its own gravity (this is eventually stopped due to electron degeneracy pressure) and into a white dwarf where it will continue to cool and fade away

-In a large star the gravity will cause it to contract more than in the above example (electron degeneracy pressure cannot prevent more contraction in this case) and will cause an explosion i.e. a supernova.
-leaving behind a black hole or neutron star

pls be on the spec I didn't memorise all of that for nothing lmao