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Physics Paper 2, Nov/Dec. 2013  
Questions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Main
General Comments
Weakness/Remedies
Strength
















Question 9

Question 9

            Electrons from a hot cathode are accelerated from rest to a target in a vacuum
            Tube maintained at a potential difference of 180V.  Calculate the velocity of the
            electrons on reaching the target.
            [ Mass of an electron = 9.1 x 10-31 kg; charge of an electron = 1.6 x 10-19 C]
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comments

Unpopular question and was poorly handled.  Unit was either wrong or missing
 entirely.  Almost all the candidates could not work it out.

 

The expected answer is:

            ½ mv2     =    eV                                                                                         
            ½  x  9.1 x 10 -31 x v2 =  1.6 x 10-19 x 180                                                 
             V  =  7.96  x  106 ms-1                                                                                
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