OCR Physics B G495 Field and Particle Pictures June 21st 2011 Exam Thread

Reckon saying "make the core fatter" would get the mark for the cross sectional area point?

Increase permeance? Balls. Definitely read that wrong, could've sworn that it said increasing the flux...That's what you get for being confident

I put increasing the current and number of turns, but if it said increase the permeance, then those are definitely wrong!

for the x-ray question did anyone get alot of people dying?!

435 painful, agonising deaths.

Dammit :/ I got 435 then divided by 100 for some reason :/ I thought you had to divide 3% by 100 to get 0.03 because 0.03 is like the proportion of people who would die per sievert

Dammit :/ I got 435 then divided by 100 for some reason :/ I thought you had to divide 3% by 100 to get 0.03 because 0.03 is like the proportion of people who would die per sievert

it said if the current and number of turns were kept the same so i cant see them awarding marks for that dude ... reading the question twice might of helped!

laminating the core doesnt increase the permeance, it increases the total flux... i think they were driving at larger area, shorter length or higher permeability material (they never said it was iron, so i said use an iron core)

overall a good paper, a few OCR moments where you just go "WTF is that question asking?!" but mostly good.

A few answers : 9 x 10^9 for the 1 sig fig number of electrons?
speed for relativistic im hoping i put 450 x 10^6 odd, cus other people seem to have that lol...
i got 4.4 people (so 4) for the cancer one... in 25 years that seemed pretty ok to me, but i still said unnecessary risk for the next bit etc

last question, what the hell did they want? I talked about measuring the frequency of the laser, and cus speed of light is DEFINED as w/e and a second is DEFINED theres no error in those values, so you can get a very precise f and so a very precise lamda using v = f lamda... not sure how it really helps you measure distance tho :/ i basically just bull****ted hehe

Dammit :/ I got 435 then divided by 100 for some reason :/ I thought you had to divide 3% by 100 to get 0.03 because 0.03 is like the proportion of people who would die per sievert

did you manage to do it in the end?
I tried finding the mass with E=mc^2, then using KE = 1/2 mv^2?! but V was something like 3.8x10^8

I GOT 17!!! ***t!! dont know how i got that if u all got 435....

I got 17.4 too. What was the initial amount of people I can't remember? Because if it's in the thousands then 435 like other people are saying sounds too high to me, if the data is based on reality I don't think an x ray giving that much dangerous radiation would be allowed

what total mark i need to get out of 600 to get a A?