HSC Physics Question Thread

[Happy Physics Land]

Hey Guys!

I have a physics research assessment coming up and there is a section that asks me to assess the validity, reliability and accuracy of the websites that I collected my information from. What do you guys reckon I should definitely have to evaluate these features?

Thank you lads

Best Regards
Happy Physics Land

[RuiAce]

Hey Guys!

I have a physics research assessment coming up and there is a section that asks me to assess the validity, reliability and accuracy of the websites that I collected my information from. What do you guys reckon I should definitely have to evaluate these features?

Thank you lads

Best Regards
Happy Physics Land

For a second hand investigation:

Validity - Does the information you obtain actually address the criteria of the question
Reliability - Is there consistency in your sources (cross referencing would be a good idea here...)
Accuracy - This is a bit hard for a second hand investigation as the accuracy of what you obtain is really subject to question - how can you really be sure of if you're obtaining the most accurate data. Perhaps reputable sources is what you want here

[Happy Physics Land]

For a second hand investigation:

Validity - Does the information you obtain actually address the criteria of the question
Reliability - Is there consistency in your sources (cross referencing would be a good idea here...)
Accuracy - This is a bit hard for a second hand investigation as the accuracy of what you obtain is really subject to question - how can you really be sure of if you're obtaining the most accurate data. Perhaps reputable sources is what you want here

Thanks heaps Rui! But do you reckon l should be doing cross referencing for accuracy and reputable sources for reliability??

[RuiAce]

Thanks heaps Rui! But do you reckon l should be doing cross referencing for accuracy and reputable sources for reliability??

Yep. They do mix between each other for a second hand investigation

[jamonwindeyer]

No worries, it was probably me being a bit confusing.

Last thing, so for a bar magnet moving through the coil. For your example, if the poles were reversed in the bar magnet. This would cause the induced magnetic field to be in the opposite direction, correct?

I think I was confusing myself by taking the direction of the moving bar magnet as the direction it was decreasing, opposed to looking at the actual magnetic field line directions.

You are spot on! The magnitude would be identical, but the field lines would be in the opposite direction, and so everything would swap!! 

[jamonwindeyer]

For a second hand investigation:

Validity - Does the information you obtain actually address the criteria of the question
Reliability - Is there consistency in your sources (cross referencing would be a good idea here...)
Accuracy - This is a bit hard for a second hand investigation as the accuracy of what you obtain is really subject to question - how can you really be sure of if you're obtaining the most accurate data. Perhaps reputable sources is what you want here

Yeah I concur, I did a massive research journal task for my HSC, and I took the approach of assuming that reputable sources were accurate, and through cross referencing with these sources, I could evaluate the accuracy of other sources. Another potential idea for you HPL 

[Happy Physics Land]

Yeah I concur, I did a massive research journal task for my HSC, and I took the approach of assuming that reputable sources were accurate, and through cross referencing with these sources, I could evaluate the accuracy of other sources. Another potential idea for you HPL 

That's what I am trying to do right now hehehehe

But thanks guys for your assistances, they were quite helpful!

[jakesilove]

That's what I am trying to do right now hehehehe

But thanks guys for your assistances, they were quite helpful!

From my understanding, cross-referencing is reliability and credentials of author etc. is accuracy. Like everyone else has said, these readily cross over, but I know at least that I was marked correctly when I used the above methodology. Regardless, it's all about waffling on for a paragraph or two, so I'm sure you'll manage to get the marks!

Jake

[Happy Physics Land]

From my understanding, cross-referencing is reliability and credentials of author etc. is accuracy. Like everyone else has said, these readily cross over, but I know at least that I was marked correctly when I used the above methodology. Regardless, it's all about waffling on for a paragraph or two, so I'm sure you'll manage to get the marks!

Jake

Maybe I will just do cross-referencing and credentials for both reliability and accuracy to cover my bases

[jamonwindeyer]

waffling on for a paragraph or two

The only time this works in HSC Physics 

[jakesilove]

Maybe I will just do cross-referencing and credentials for both reliability and accuracy to cover my bases

Alternatively, claim that you tried to do research for this area of the curriculum. Say you received multiple solutions to the same problem when cross-checking your information, but all of the people offering ideas had fantastic credentials.

Accuracy = Good? Bad? Reliability = Good? Bad?

?

Profit.

[Neutron]

Yo yo yo, it's been a while!

I have a prac assessment on Friday (it's a written prac, so like data analysis as opposed to some hands on stuff :/) and we basically have to know all the pracs we've done in Motors and Generators as well as Ideas to Implementation.. For the prac we did for Hertz' experiment (basically we had an induction coil and a nearby radio and we just listened to the static when the induction coil was turned on), I read somewhere that the lower frequency EM wave produced but the induction coil, the larger the static noise is? I was wondering why that is.. And also, does the induction coil have to be connected to an AC or DC supply? Or does it not matter? Thank you guys so much! Ahh I'm having trouble preparing for this assessment cause normally I just do past papers but this time the teacher's only provided one so yeah.. How do you guys normally prepare for written pracs?

Thank youuu! :')

Neutron

[jamonwindeyer]

Yo yo yo, it's been a while!

I have a prac assessment on Friday (it's a written prac, so like data analysis as opposed to some hands on stuff :/) and we basically have to know all the pracs we've done in Motors and Generators as well as Ideas to Implementation.. For the prac we did for Hertz' experiment (basically we had an induction coil and a nearby radio and we just listened to the static when the induction coil was turned on), I read somewhere that the lower frequency EM wave produced but the induction coil, the larger the static noise is? I was wondering why that is.. And also, does the induction coil have to be connected to an AC or DC supply? Or does it not matter? Thank you guys so much! Ahh I'm having trouble preparing for this assessment cause normally I just do past papers but this time the teacher's only provided one so yeah.. How do you guys normally prepare for written pracs?

Thank youuu! :')

Neutron

Sup Neutron!! Long time no see 

Okay, so about the low frequency EM producing larger radio static, that is simply because radio waves ARE extremely low frequency waves. I'd imagine that the higher you go, you start to slide out of the range of the receiver in the radio. I have no idea what this range would be, but that would be my response. The radio receiver would be tuned to listen to those low frequency waves 

Usually induction coils are connected to a DC power supply. A special type of transformer apparatus is used to 'step up' a reasonably low DC voltage to one high enough to induce sparking. The specifics of construction and how it works are a little complex, but yep, DC 

Edit: It might still actually be connected to AC mains and then rectified by the apparatus, I think it depends on the specific coil.

Practical tests are tricky. I'd brush up on your terms like accuracy, validity, reliability, and practice suggesting improvements to experiment design. Beyond that, remember all the practical tasks you've done in class; including the dependent and independent variables in each case, and be ready to analyse the data from those prices in some way. Not much else you can do for these, I never did a fully written practical task, so maybe someone else might have some better advice. Hope this helps Neutron!! 

[Neutron]

Ohh thank you so much! That was super helpful I have another question though.. Is there a relationship between the spark gap and the maximum distance the static can be received? If so, what is the relationship? Is it the larger the spark gap, the greater the distance? I have no idea, I'm making it up :') Does widening the spark gap increase the wavelength of the radio wave produced or something? Thank you so much guys!

Neutron

[jamonwindeyer]

Ohh thank you so much! That was super helpful I have another question though.. Is there a relationship between the spark gap and the maximum distance the static can be received? If so, what is the relationship? Is it the larger the spark gap, the greater the distance? I have no idea, I'm making it up :') Does widening the spark gap increase the wavelength of the radio wave produced or something? Thank you so much guys!

Neutron

Just as a warning, you are straying into non-assessable content here.

Well, a larger spark gap would mean a higher breakdown voltage, which would mean a greater acceleration of electrons when the spark occurs. Thus, yes, the magnitude of the resultant EM waves would increase with the size of the spark gap, at least quantitatively, I'm not sure of the nature of the relationship there, but that would be my best guess 

As an edit, in terms of your question, this wouldn't likely translate to any measurable difference in the distance you can detect the static. Especially radio waves.

It's important to note that Spark Gap Transmitters (which is what you are looking at here) radiate EM energy across the EM spectrum, it just so happens that it is focused at the lower (radio) end. That's why you can hear the static interference on any radio channel (PS - the frequencies generated more intensely by these sort of gaps are now internationally banned for radio communication, because of this interference issue.[/b] Basically, the frequency spectrum of the waves is dependent on the construction of the coil. The EM wave production is caused by the oscillation of electrical charge, assisted by circuit elements called inductors and capacitors, and it is the value of these elements which affects the frequency. I don't think the size of the gap would have a measurable effect