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HSC Physics Marathon[NEW SYLLABUS]

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DrDusk:
Question 4:
This is definitely a kind of question you can be asked because the Math itself is simple but requires you to make an observation that may be difficult to spot =)

Definitely more of a challenging uniform circular motion/Magnetism question!

fun_jirachi:
My answersHope these are right! :)
i) Into the page. (Used left-hand grip rule)
ii)

DrDusk:

--- Quote from: fun_jirachi on October 13, 2019, 07:19:10 pm ---My answersHope these are right! :)
i) Into the page. (Used left-hand grip rule)
ii)



--- End quote ---
Wowie well done! Your smashing them. However you may want to re-consider your part (i)  ;)

frog0101:

--- Quote from: DrDusk on October 04, 2019, 04:56:28 pm ---Question 3 answer.

They wont always provide a diagram. Sometimes there really is a lot of info so you gotta learn to stay calm and work your way through it.

A question like this can definitely appear in a trial or hsc exam.

--- End quote ---

I thought that since the electron is being accelerated horizontally by the electron gun,
Not sure that the way I am visualising this is correct (horizontal acceleration and then vertical acceleration), but wouldn't only the horizontal parallel plates accelerate the electron in the vertical direction?
Thanks

THSCStudyOnly:
My solution, I think it may be easier to see, but bit longer to do :P ;D
Spoileri) Out of page (using rhpr but flipped hand because electrons)

ii) Using mass spectomrtry equation
i.e. qvB=mv2/r
r = mv/qB
rearranging v = rqB/m .............. (1)

Now Consider:
K = (1/2)mv2
rearrange to make v subject: v = sqrt(2K/m) ............... (2)

Equating (1) and (2)
sqrt(2K/m) = rqB/m
2K/m = (r2q2B2)/m2
Just rearrange to make B2 subject
B2 > 2Km/q2r2
B > sqrt((2Km/q2r2))
(Now: q=e and r=d)
B > sqrt((2Km/e2d2))
There may be lots of errors because it is too messy to read with this crap formatting.

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