OCR A Level Paper 2: Exploring Physics A 24th May General Discussion

last years unified was quite easy so im expecting a f*****g hard paper and for paper 2 itll probably be in the middle of hard and easy. im just praying i get a b overall at least because i messed up paper 1 soo bad

imagine i wrote taking pictures to find the velocity of the marble. killl me nowwwww

In this question, two marks are available for the quality of written communication. To explain the laws of electromagnetic induction (Faraday’s law and Lenz’s law) Faraday introduced the concept of magnetic flux. Describe how the flux model is used in these laws. Start by defining magnetic flux and magnetic flux linkage. This would be a nice question.

magnetic flux = BA 1 meanings of B and A, i.e. flux density or field strength and area ⊥ to it 1 magnetic flux linkage refers to the flux linking/passing through a coil; 1 and equals N × flux where N is the number of turns (of the coil) 1 Faraday’s law: induced e.m.f./voltage is proportional to rate of change of flux linkage through it /correct mathematical formulation/AW 1 Lenz’s law: the direction of the induced e.m.f./voltage is such as to oppose the motion/change that produced it 1 relationship of Lenz’s law to conservation of energy or other valid explanation/discussion/description.

Although there is a relatively sufficient probability of there being a question considering Faraday's law of electromagnetic induction, perhaps a graph whereby one has to analyze and evaluate the relationship. Other tiered questions may include experimental analysis of a radioactive source to determine the presence of particular radiation (alpha, beta or gamma), or maybe the notoriously forgotten half-life experiment involving protactinium-234. It would be nice for there to be a photoelectric experiment to determine planks constant using LEDs, but I don't that will come up.

Perhaps the formation of x-ray photons, the mechanism of an x-ray tube, and maybe the scattering mechanisms (pair production, simple scatter, Compton scattering and photoelectric effect); there could be Bremsstrahlung radiation, however, this is an extensive addition to the spec.

You could either use motion sensors to automatically calculate the initial velocity within a fraction of second or light gates, however, the light gates wouldn't be as reliable. Any method of calculating would be sufficient, it's only one method mark.

did anyone write about drawing a graph of vsquared against x?

did anyone write about drawing a graph of vsquared against x?

Yeah, that's the right way. Otherwise you can't easily show that v^2 is directly proportional to x (straight line through the origin), also you can't get F otherwise (unless you use logs or something). Although now that I think about it you could have used logs as well I guess.

I have no idea what Bremsstrahlung radiation actually is do you think its worth looking into it jsut incase?

I really agree with the rest of the stuff

When the beam electrons "knock" electrons in the higher energy levels of an atom to lower energy level, occupying lower vacancies, thereby these electronic transitions result in x-ray photon emission, they probably won't ask (In the purple box of the textbook).

I have no idea what Bremsstrahlung radiation actually is do you think its worth looking into it jsut incase?

I really agree with the rest of the stuff

did anyone write about drawing a graph of vsquared against x?

yeah then i wrote to find the f you do gradient*mass/2 hope that is right because i messed up the method and for the luminosity 6 marker that the luminosity is directly proportional to r2 so higher luminosity higher radius for why the sun has a bigger radius than the trappist star. praying i get decent on the 6 markers because i messed up the maths questions

since V^2 is your independent variable it should be plotted on the x-axis, and the dependent variable, x on the y-axis

I didn't do this and I don't think this matters. On numerous times throughout the course there are graphs plotted the opposite way round (force-extension comes to mind)

Personally, I think the next 2 papers would be either easier or of the same standard, considering that those designing the exam would not have received feedback of the difficulty until after the scripts have been marked, this paper was slightly harder than last year, though I may have done better on this paper, since the tiered questions were free giveaways, we never know. The papers should be getting harder, if this is the "Harder paper" then we are in for a treat. Physics has high-grade boundaries almost every student who does the subject is naturally gifted, there should establish a definite boundary or at least increase the distribution of A*s.