sy37
Active Member
- Joined
- Jun 22, 2014
- Messages
- 323
- Gender
- Male
- HSC
- 2015
-
Looking for HSC notes and resources? Check out our Notes & Resources page
HSC Physics Marathon 2013-2015 Archive (1 Viewer)
- Thread starter Magical Kebab
- Start date
- Status
turnerloos
TAFE Executive Officer
TQuadded
Breaking the limits.
re: HSC Physics Marathon Archive
A black body refers to a theoretical object that perfectly absorbs the radiation that it is subjected to. This results in heat building up, and radiation is emitted. Proposed by Planck, quantum theory states that for these black bodies, light is not continually absorbed, but rather is absorbed in small packets also known as 'quanta's of energy. Light is absorbed in whole numbers (e.g. 1, 5, 300 quanta's); it either absorbs a quanta, or not at all. This suggests that the intensity of light absorbed is independent of its frequency, but is rather affected by the amount of energy in a quanta of light. This was, however, later improved by Einstein, where he showed via 'E = hf', that frequency determines whether or not a photon (renamed from quanta of energy) is absorbed by a black body.
Shit, this is my weakest point.
A black body refers to a theoretical object that perfectly absorbs the radiation that it is subjected to. This results in heat building up, and radiation is emitted. Proposed by Planck, quantum theory states that for these black bodies, light is not continually absorbed, but rather is absorbed in small packets also known as 'quanta's of energy. Light is absorbed in whole numbers (e.g. 1, 5, 300 quanta's); it either absorbs a quanta, or not at all. This suggests that the intensity of light absorbed is independent of its frequency, but is rather affected by the amount of energy in a quanta of light. This was, however, later improved by Einstein, where he showed via 'E = hf', that frequency determines whether or not a photon (renamed from quanta of energy) is absorbed by a black body.
re: HSC Physics Marathon Archive
might need to mention ultraviolet catastrophe and how quantum theory explained this, not too sure though i'm also shit at this
leehuan
Well-Known Member
- Joined
- May 31, 2014
- Messages
- 5,805
- Gender
- Male
- HSC
- 2015
TQuadded
Breaking the limits.
re: HSC Physics Marathon Archive
I have no clue what that is. Other than that what do you think of the response? I actually barely understand the topic, I just put the important words I remembered (e.g. quanta, photon, packets) into the basic idea I had about this topic.
re: HSC Physics Marathon Archive
A black body is a theoretical object that absorbs all incoming radiation, as radiation is absorbed the black body is heated and begins to emit EM radiation at a range of frequencies -- therefore the wavelength of radiation will vary with temperature. The classical wave theory of light suggested that as the absorbed energy decreased in wavelength (heated up), radiation intensity would approach infinity, thereby violating the conservation of energy. This is theorised for UV rays and therefore dubbed the 'ultraviolet catastrophe'. Quantum theory explained this as it suggested that the radiation absorbed and emitted by a black body comes in discrete packets known as 'quanta', and is not continuous, meaning that it would not increase infinitely -- thereby explaining the 'ultraviolet catastrophe'.
i'll try my best lol:
A black body is a theoretical object that absorbs all incoming radiation, as radiation is absorbed the black body is heated and begins to emit EM radiation at a range of frequencies -- therefore the wavelength of radiation will vary with temperature. The classical wave theory of light suggested that as the absorbed energy decreased in wavelength (heated up), radiation intensity would approach infinity, thereby violating the conservation of energy. This is theorised for UV rays and therefore dubbed the 'ultraviolet catastrophe'. Quantum theory explained this as it suggested that the radiation absorbed and emitted by a black body comes in discrete packets known as 'quanta', and is not continuous, meaning that it would not increase infinitely -- thereby explaining the 'ultraviolet catastrophe'.
re: HSC Physics Marathon Archive
this is actually much more complex than it looks... many people assume 34 m to be the flight's maximum height and do not account for the range in their equations and get 29.8m/s (which is close but not correct). The thing is if you do this, the bird could reach 34 m high but only 10m wide. the answer is 30m/s (may be a decimal there) and uses quite complex simultaneous equations - the answer would be on the 2012 hsc marking guidelines.hgow do we do this:
re: HSC Physics Marathon Archive
Analyse Einstein's Theory of Special Relativity and the evidence supporting it as an application of this model of scientific method.
Can someone do this please? Or write up a plan/summary
Analyse Einstein's Theory of Special Relativity and the evidence supporting it as an application of this model of scientific method.
Can someone do this please? Or write up a plan/summary
re: HSC Physics Marathon Archive
- Scientists did not know the medium of travel for light (other waves had a medium so logically light, being a wave, was also thought to have one) observation and problem raised
- The aether was the proposed medium of travel for light new hypothesis
- Michelson and Morley set out to prove the existence of the aether by measuring the relative velocity of the Earth through the aether experiment
- Outline the M&M experiment and its null result despite repeated experiments with precise instruments (changes in interference patterns should be observed as the interferometer was rotated, however this did not occur) collection of data and analysis of result --> lack of support
- Einstein's special theory of relativity, which introduced the constancy of the speed of light. This accounted for the null result and made the aether model redundant (because there would be no differences in interference patterns)
- Evidence supporting Einstein's theory in later periods (muon decay, atomic clocks and such) New theory or law
I think it would be something along these lines
Analyse Einstein's Theory of Special Relativity and the evidence supporting it as an application of this model of scientific method.
Can someone do this please? Or write up a plan/summary
- Scientists did not know the medium of travel for light (other waves had a medium so logically light, being a wave, was also thought to have one) observation and problem raised
- The aether was the proposed medium of travel for light new hypothesis
- Michelson and Morley set out to prove the existence of the aether by measuring the relative velocity of the Earth through the aether experiment
- Outline the M&M experiment and its null result despite repeated experiments with precise instruments (changes in interference patterns should be observed as the interferometer was rotated, however this did not occur) collection of data and analysis of result --> lack of support
- Einstein's special theory of relativity, which introduced the constancy of the speed of light. This accounted for the null result and made the aether model redundant (because there would be no differences in interference patterns)
- Evidence supporting Einstein's theory in later periods (muon decay, atomic clocks and such) New theory or law
Last edited:
re: HSC Physics Marathon Archive
obsrvation: speed of light through aether wind did not change as per Michelson and Morley experiment
Problem: Because the Michelson Morley experiment was valid and reliable it meant that there was no Aether as it was known that earth moves around the sun.
New Hypothesis: No stationary reference frame exists, but rather inertial and non-inertial reference frames. The speed of light is constant in all reference frames meaning space and time become relative.
Experiment: Einstein's thought experiments.
No data to collect or analyse, so lack of support for this hypothesis.
Experiment: Muons and Atomic clock.
Through collection of data and analysis from experiments it was seen: Muons are detected (explain why to do with time dilation/length contration), and atomic clocks are different (explain why)
This provided the necessary support, and Einsteins Theory of Special Relaivity was developed.
OBVIOUSLY IT NEEDS MORE EXPLAINING but this is a guide
obsrvation: speed of light through aether wind did not change as per Michelson and Morley experiment
Problem: Because the Michelson Morley experiment was valid and reliable it meant that there was no Aether as it was known that earth moves around the sun.
New Hypothesis: No stationary reference frame exists, but rather inertial and non-inertial reference frames. The speed of light is constant in all reference frames meaning space and time become relative.
Experiment: Einstein's thought experiments.
No data to collect or analyse, so lack of support for this hypothesis.
Experiment: Muons and Atomic clock.
Through collection of data and analysis from experiments it was seen: Muons are detected (explain why to do with time dilation/length contration), and atomic clocks are different (explain why)
This provided the necessary support, and Einsteins Theory of Special Relaivity was developed.
OBVIOUSLY IT NEEDS MORE EXPLAINING but this is a guide
Mathsisfun15
Active Member
- Joined
- Apr 25, 2015
- Messages
- 157
- Gender
- Male
- HSC
- 2015
re: HSC Physics Marathon Archive
Hypothesis: light ha smedium
Problem raised: ligjht needs medium
Experiment, data and results: Michelsen and Morley (describe briefly) and then analyse implications
Support for hupothesis: results show there is none
Then Einstein hypothesis on relativity
the support is his thought experiments as well as mesons and planes
New theory - Special relativity
Observaion: all known waves need medium
Analyse Einstein's Theory of Special Relativity and the evidence supporting it as an application of this model of scientific method.
Can someone do this please? Or write up a plan/summary
Hypothesis: light ha smedium
Problem raised: ligjht needs medium
Experiment, data and results: Michelsen and Morley (describe briefly) and then analyse implications
Support for hupothesis: results show there is none
Then Einstein hypothesis on relativity
the support is his thought experiments as well as mesons and planes
New theory - Special relativity
re: HSC Physics Marathon Archive
A student claims that a DC generator is an 'electric motor in reverse'. Analyse this claim with reference to the struture and function of a simple DC generator and an eletric motor
4 MARKS
A student claims that a DC generator is an 'electric motor in reverse'. Analyse this claim with reference to the struture and function of a simple DC generator and an eletric motor
4 MARKS
re: HSC Physics Marathon Archive
"The students claim that a DC generator is an electric motor in reverse is basically correct. The components in each are almost identical but, with the generator, work is done to supply the mechanical energy to rotate the coil, which then provides electrical energy via the split-ring commutator to run an external circuit, while in a motor the reverse applies, with the supply of electrical energy producing a current which flows in through the split-ring commutator to create a torque, causing the coil to rotate, which provides a source of mechanical energy to do work."
They also included a diagram, but it's nothing special, just a DC generator and motor
From Success One:
"The students claim that a DC generator is an electric motor in reverse is basically correct. The components in each are almost identical but, with the generator, work is done to supply the mechanical energy to rotate the coil, which then provides electrical energy via the split-ring commutator to run an external circuit, while in a motor the reverse applies, with the supply of electrical energy producing a current which flows in through the split-ring commutator to create a torque, causing the coil to rotate, which provides a source of mechanical energy to do work."
They also included a diagram, but it's nothing special, just a DC generator and motor
TQuadded
Breaking the limits.
re: HSC Physics Marathon Archive
yep pretty much, just one with a handle to produce the work
- Status