**Physics...Before/After**

Bears and Vodka

cocopopsxx wrote: »

Is the particle physics option worth it? My teacher didn't do it with us but he gave us the notes- looks fairly daunting but I've heard the questions aren't that bad. How long does it take to do it approximately?

It's very easy if you know modern physics well because it kind of follows on from that. I'd say it would take a couple of hours to get a grip on it. Learn the Cockroft & Waltons accelerator diagram, the nuclear equation for it (Li + H => He + He + Q), learn pair production, positrons, anti-particles, and then the confusing stuff at the end like baryons and mesons and make sure you know the Quark composition of a proton and a neutron.
Questions on particle physics are very straightforward.

Nitsuj

Our teacher spent a double class before the mocks doing particle physics and never really touched on it again. It's pretty simple and short. Not to mention, always a guaranteed question.

clio94

Id recommend having all the experiments perfect .. Expecting joules this year Also learn all the derivations, definitions & non mandatory experiments - these come up every year and are usually worth about 30 marks.

You can't really predict much, better off just having a clear understanding of everything!

jos360

If anyone needs a summary of modern physics!
The text is mirrored tho, sorry

Dicksboro_man

Lads, anyone know how physics is marked if you're asked for, lets say,an example of a use for a concave lens or something.. and you give two answers, of which only one is right. Is it gonna be like biology, where each wrong answer cancels out 1 right one, or is it gonna be like maths where they look at it as 2 attempts and they count your best one?

Bears and Vodka

They correct your first attempt and that's it.

Nitsuj

subz3r0 wrote: »

They correct your first attempt and that's it.

dammit

mathstalk

subz3r0 wrote: »

They correct your first attempt and that's it.

What if you write your answer in a way so that there is no definite "first attempt"?

For example:


EDIT: This is a serious question by the way.

Jimdwyer

cocopopsxx wrote: »

Is the particle physics option worth it? My teacher didn't do it with us but he gave us the notes- looks fairly daunting but I've heard the questions aren't that bad. How long does it take to do it approximately?

If you have the time it could be worth it as it's quite predictable but if not I think you should focus on perfecting what you know already

Dwellingdweller

I really wish the teachers in my school would teach things in a more exam-oriented way. Like, in Physics, we didn't do one test paper in class in two years. 95% of classes consisted of us sitting half-asleep listening to our teacher read notes from the textbook. Probably the worst way to learn Physics imaginable. Seriously, if I was teaching Physics I would print off the physicsteacher.ie stuff, do exam paper questions every day with the class, and then by the time the exam came around, they'd be certified A-grade students.

Reading notes from a textbook is the worst way to approach subjects for the LC, there's just so much detail that's not needed and which isn't accounted for in the marking scheme. Colossal waste of time on my teachers' part.

Bears and Vodka

mathstalk wrote: »

What if you write your answer in a way so that there is no definite "first attempt"?

For example:


EDIT: This is a serious question by the way.

In relation to that particular question my (very good) physics teacher says: 'Circular accelerators produce higher energy collisions' is a much better answer because it's a scientific explanation. 'Take up less space' is a general statement, take up less space, so what like? It has nothing to do with physics.

Wanchor

Here's a Chief Examiners report on Physics higher level. Yep, kinda bored.

Dwellingdweller

Does anybody know if, when they ask you to define the Newton, they'd accept something like this?

Define the Newton.
The newton is the kilogram per metre squared. (kgms^-2)

Or would that get no marks?

RedTexan

1 newton is that force which gives an object of mass 1kg an acceleration of 1m\s^2. probably best off sticking with the definition

mathstalk

Dwellingdweller wrote: »

Does anybody know if, when they ask you to define the Newton, they'd accept something like this?

Define the Newton.
The newton is the kilogram per metre squared. (kgms^-2)

Or would that get no marks?

I don't think the Newton is the kilogram per metres squared, if anything, it would be the kilogram per metres seconds squared. I'd stick to the plain definition though:

The Newton is the force that gives a mass of 1kg an acceleration of 1ms^-2

Dwellingdweller

RedTexan wrote: »

1 newton is that force which gives an object of mass 1kg an acceleration of 1m\s^2. probably best off sticking with the definition

mathstalk wrote: »

I don't think the Newton is the kilogram per metres squared, if anything, it would be the kilogram per metres seconds squared. I'd stick to the plain definition though:

The Newton is the force that gives a mass of 1kg an acceleration of 1ms^-2

It's definitely the kgms^-2 as well, but I think I'll stick to the plain definition if it comes up, in case the other way isn't on the marking scheme. Thanks

mathstalk

Demonstrative and mandatory experiments revised (Well, other than the ones that came up last year )

Dwellingdweller

Hey guys, what's the importance of the depletion layer in p-n junctions? I know that negative electrons flow from the n to the p layer, and the positive free holes, as there's a potential difference between the layers but I don't understand where the depletion layer comes into play.

Osric

Prevents current flowing based on how diode is connected in circuit (forward-biased or reverse). If reverse-biased, depletion layer thickened - even less free charge carriers. If forward-biased, depletion layer reduced as opposite charge forced into each end, cancelling it out and allowing current to flow

I think

RedTexan

Dwellingdweller wrote: »

Hey guys, what's the importance of the depletion layer in p-n junctions? I know that negative electrons flow from the n to the p layer, and the positive free holes, as there's a potential difference between the layers but I don't understand where the depletion layer comes into play.

For a the semi-conductor to conduct there must be a voltage supplied which is greater than the depletion layer (and it has to be in forward bias of course), if the semi-conductor is connected in reverse bias the depletion is broadened. There are no charge carriers available in the depletion layer, when the depletion layer is overcome a large current can flow. That's pretty much the lot

Dwellingdweller

RedTexan wrote: »

For a the semi-conductor to conduct there must be a voltage supplied which is greater than the depletion layer (and it has to be in forward bias of course), if the semi-conductor is connected in reverse bias the depletion is broadened. There are no charge carriers available in the depletion layer, when the depletion layer is overcome a large current can flow. That's pretty much the lot

Ah! So the base voltage required for current to flow in the semiconductor has to overcome the PD depletion layer. And if connected in reverse bias, because the positive holes are attracted to the negative current flowing into the anode, and the negative electrons are attracted to the positive current flowing into the cathode, the depletion layer broadens. I get it! Thanks

RedTexan

And that's the reason only dc can flow in a diode! Because current flow only one way through the semi-conductor

mathstalk

Here's something you can print out to test your knowledge of definitions and figure out which ones to work on.

HeaneyBabe

I'm so screwed. I just can't get anything. What;s the best way to study?

water_piano

HeaneyBabe wrote: »

I'm so screwed. I just can't get anything. What;s the best way to study?

Without the Internet

Considering going back to pass for Physics. Anything to look out for on the paper that's different to Higher Level?

Chuchoter

RedTexan wrote: »

And that's the reason only dc can flow in a diode! Because current flow only one way through the semi-conductor

No, AC can flow through a diode. It acts as a rectifier. DC can only flow through a diode in forward bias.
Also
A newton is that force that gives 1 kg an acceleration of 1ms^2

Wesc.

I've decided to do the whole course apart from experiments tomorrow. Don't know how I'll cope.. but I have two bottles of red bull in preparation!

Chuchoter

We should post questions to test eachother because I have no ****ing clue what to look at anymore.
First question:
What can affect the accuracy of the stretch string experiment?

Nitsuj

Just asked a question on 2xm about the marking and they said they give the best attempt UNLESS you have two contradicting answers, like you state that the neutrino is positive and negative.