Physics marathon (hsc) (1 Viewer)

[lemon1]

A calculation question to get everyone on their game:

Definitely C

just find out the current which ends up being 22.86
then substitute the values into f=bil

 

[124]

wow quanta to quarks is a lot..

 

[dawooddaman]

i have my notes but i'm still scared. re summarising to remember and then tomorrow i'm gonna highlight the important stuff and then start re writing those. Is that a good idea?

I think everyone, were human I guess, but remember this in exam mode thing come to you like that.

All you need is a 82+ and you’re in band 6 level, chillax you'll be sweet

 

[freeeeee]

Since X-rays have extremely short wavelength, Braggs though that by subjecting a crystal structure to X-ray beams information about lattice structure could be gathered. They used an X-ray tube to emit uniform X-ray beams through collimators towards the lattice structure so they remained parallel as they hit the plane. These X-rays were reflected by different lattice planes and some were detected by the detector. These resulted in an interference pattern which the Braggs analysed mathematically (don't think the whole equation is necessary) to find the distance between the planes. This was repeated from different orientation and the same distance was found, suggesting a uniform 3D pattern.

I think:
This discovery helped us better understand how conduction occurred --> electrons flow between lattice planes in metals. Also, improved scientific understanding on resistance --> lattice could obstruct electrons. It also enabled more understanding into doping by enhancing scientist's understanding of crystal structures?



btw: Any other projectile motion question like that electron one ?

nice answer, just addtional stuff --> he applied mathematical analysis to determine relationships between spacing of cryustal planes, angles of reflection and the wavelengths of radiation. they key impact as you said is the doping and the regular spacing

 

[RishBonjour]

Do we need to know some metals/alloys/ceramic that exhibit superconducting properties and their critical temperatures? or in a question do they give this info to us?

I don't think so. but Ill write some here so incase they ask, this image pops up in my brain
I think aluminium - 1.2K
niobium aluminium-germanium alloy- 21K
YBCO- 90K

 

[freeeeee]

I don't think so. but Ill write some here so incase they ask, this image pops up in my brain
I think aluminium - 1.2K
niobium aluminium-germanium alloy- 21K
YBCO- 90K

lol nice memory

 

[lemon1]

Since X-rays have extremely short wavelength, Braggs though that by subjecting a crystal structure to X-ray beams information about lattice structure could be gathered. They used an X-ray tube to emit uniform X-ray beams through collimators towards the lattice structure so they remained parallel as they hit the plane. These X-rays were reflected by different lattice planes and some were detected by the detector. These resulted in an interference pattern which the Braggs analysed mathematically (don't think the whole equation is necessary) to find the distance between the planes. This was repeated from different orientation and the same distance was found, suggesting a uniform 3D pattern.

I think:
This discovery helped us better understand how conduction occurred --> electrons flow between lattice planes in metals. Also, improved scientific understanding on resistance --> lattice could obstruct electrons. It also enabled more understanding into doping by enhancing scientist's understanding of crystal structures?



btw: Any other projectile motion question like that electron one ?

Weren't the x-rays diffracted by the structure, which showed the alignment/spacing between the atoms in the crystalline structure? Which allowed further mathematical analysis etc..?

still a band 6 answer i assume

 

[RishBonjour]

lol nice memory

short term= really good
after 1 week= I will forgot everything. (downfall of cramming)


Yeah X-rays were diffracted, but only those that reflected parallel were detected I think. Could be wrong though.
Its an outline dot point so really. 4-5 CORRECT steps= full marks

 

[freeeeee]

Weren't the x-rays diffracted by the structure, which showed the alignment/spacing between the atoms in the crystalline structure? Which allowed further mathematical analysis etc..?

still a band 6 answer i assume

ye your right, when the x-ray penetrated through the crystal lattice it scattered in all directions, these rays will then interfere constructively and destructively (diffraction) resulting in a maximum or minimum respectively. The Braggs then analysed the distance between adjacent maximums to derive relationships through mathematical anaylsis like you said.

 

[nerdasdasd]

The orbit of earth is elliptical not circular, will the hsc ever deal with elliptical orbits in relation to say, an satellite orbiting an planet ?

 

[HSC2012RESOURCE]

Hey guys can you please post some difficult multiple choice questions which you guys have encountered over time.

Lets see if we can all solve them.

 

[nerdasdasd]

Hey guys can you please post some difficult multiple choice questions which you guys have encountered over time.

Lets see if we can all solve them.

Here is plenty of mc for you. It is sorted by topic too.
https://skydrive.live.com/redir?resid=6A56337708D441B4!15550&authkey=!AGmhpX-hxMS2yNA

 

[freeeeee]

most the difficult multiple choice Qs are for motors, Success One really helps =D,

Anways Question: Outline how Hertz was able to measure the speed of radio waves and how they relate to light waves (3marks)

 

[Keelan134]

i have my notes but i'm still scared. re summarising to remember and then tomorrow i'm gonna highlight the important stuff and then start re writing those. Is that a good idea?

tis a very good idea, you recall things better by doing them, i.e rewriting your notes. Tis better then just reading,


GOOD LUCK EVERYONE, Especially those who like I also have Legal that day

 

[freeeeee]

tis a very good idea, you recall things better by doing them, i.e rewriting your notes. Tis better then just reading,


GOOD LUCK EVERYONE, Especially those who like I also have Legal that day

wow thats a killer, i dont do Legal but i assume its a lot of memorising, GL tomorrow

 

[Ichiii]

Hertz knew the frequency of the radio waves.
He then focused the radio waves onto a mirror which reflected the radio waves to produce a standing wave. He measured the half wavelengths at the points where the constructively and desconstructively interfered producing no radio waves.
He then use the wavelength which he found V=l x f and found the velocity was close to the speed of light. It also had properties similiar to light such as polarisation.

Anywhere close? Would I have to mention Maxwell and how he proposed EMR Waves?

 

[freeeeee]

Hertz knew the frequency of the radio waves.
He then focused the radio waves onto a mirror which reflected the radio waves to produce a standing wave. He measured the half wavelengths at the points where the constructively and desconstructively interfered producing no radio waves.
He then use the wavelength which he found V=l x f and found the velocity was close to the speed of light. It also had properties similiar to light such as polarisation.

Anywhere close? Would I have to mention Maxwell and how he proposed EMR Waves?

Yeh, apparently there is a lot of "ways" he measured wavelength
some textbooks say he reflected the reciever wave onto a mirror and was then able to calculate the wavelength others say that he connected the detector and receiver loop with a piece of wire and then rotated the receiver loop to create an interference pattern, from that wavelength could be measured

 

[Danstar2]

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

 

[freeeeee]

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

For a transformer to operate there must be a changing magnetic field in the primary coil to induce a current in the secondary coil, as AC electricity has fluctuating magnitude and direction it is preferred as the input current for transformers as energy can be stepped up or stepped down more efficiently relative to DC electricity.

 

[freeeeee]

Just some basic 2mark Questions:

1. Explain what is meant by drift velocity
2. Outline the photoelectric effect