the changing magnetic field in the rotor is caused by the surrounding electromagnets inducing a current and hence a magnetic field.....the constant alternation of the currents in the surrounding electromagnets causes the changing magnetic field hence the answer is C
the angle of 40 degrees was added in to trick us.... if u look closely, u will see that the electron is actually still entering the magnetic field and crossing the field lines at a perpendicular angle hence sin90 =1 therefore u disregard the value of 40 degrees and the answer becomes D... hope...
haha ur calling everyone in this thread ignorant when U DONT EVEN HAVE THE RIGHT ANSWER!!!
ur so wrong! the answer is C.... everyone in this thread agrees and unfortunately, our combined knowledge is a lot more than urs!
Re: 回复: Re: 回复: hard projectile question
u will get full marks if u get the right answer.... if u get the wrong answer however, zero marks as opposed to instead of using the 3unit formulas, using the physics formulas and having correct working but the wrong answer where u could possibly still...
thats a stupid thing to say, im a 4unit person and i found the 4unit test easier than the 3unit test.....obviously the BOS know wat is 3unit standard and wouldnt set the test to advantage 4unit kids... that would be stupid....
Re: How did you guys go?
i think ur an arrogant barstard . . . . . u need to pull your head in . . . . . the test was considered reasonably hard all round therefore no one needs to hear about how smart u are so get off ya high horse