Figure 1. A particle of charge +q, accelerated through a potential difference V to a speed v enters a magnetic field and travels in an arc of radius r.

Sunday, 26 August 2018

12:55 AM

Machine generated alternative text:
Question: 
x 
Figure 1 _ A panicle of charge +q, accelerated through a potential ditterence V to a speed v enters a magnetic field and travels in an arc of radius r. 
In the device depicted in the schematic, a singly charged positive ion, mass 2.00 x 10¯26 kg and charge 1.60 x 10-19 C, is accelerated trom rest by a potential ditterence 6.9 kV in the absence 
of magnetic fields. (Its weight is negligible in comparison with the electric and magnetic forces.) 
part 1) 
What direction is B in, in order to produce the motion shown? 
(No answer given) 
part 2) 
What is its speed atter this acceleration? 
part 3) 
It then enters, at right angles and through a small slot, into a region with a uniform magnetic field B, witn magnitude 0.68 T, which causes the ion to follow the semicircular path shown. Calculate the 
distance x trom the injection point at which the ion strikes the screen (see schematic).

 

Machine generated alternative text:
Feedback tor Part 1) 
The initial acceleration and tneretore the magnetic force qi x are to the right. q is positive, up, so must be out ottne page. (It the thumö ot your right hand is in the direction otä and your 
right index finger in the b direction, then the middle finger ot that hand, it at right angles to the others, is in the direction otä x b.) 
Marks for this submissiom 0.00/0.33. This submission attracted a penalty of 0.11 
Feedback tor Part 2) 
Jrnv2 = AK = work done on it = qV. So: 
2qv 
t' 
Don't forget to convert V to volts. 
Marks for this submissiom 0.00/0.33. This submission attracted a penalty of 0.11 
Feedback tor Part 3) 
The centripetal force that imposes the uniform circular motion is the magnetic force, and v and B are always at right angles so: 
WB — me 
2r 
qB 
2qv 
m 
2 
2mV 
Marks for this submissiom 0.00/0.33. This submission attracted a penalty of 0.11 
A correct answer 
"Out of the page" 
A correct answer is 330000, which can be typed in as follows: 
330eaa 
A correct answer is 0.12, which can be typed in as follows: 
e.12

 

 

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