Three Point Charges - General Physics - Solved Past Paper, Exams of Physics

Download Three Point Charges - General Physics - Solved Past Paper and more Exams Physics in PDF only on Docsity! 2. (25 pts) Three point charges are arranged as shown below. 0.1 m 0.3 m -3 nC 5 nC 6 nC a) Determine the electric field that the 6 nC and -3 nC charges create at the origin. |E6| = ( 8.99 × 109 ) ( 6 × 10−9 ) 0.32 = 600 N/C Since this charge is positive, the field at the origin is to the left. This makes it ~E6 = −600 î N/C |E−3| = ( 8.99 × 109 ) ( 3 × 10−9 ) 0.12 = 2697 N/C Note that at the origin the field is towards the negative charge, thus it is down: ~E−3 = −2697 ĵ N/C Therefore, the net electric field is ~E = ~E6 + ~E−3 = −600 î− 2697 ĵ N/C You could also work out the magnitude and direction. This gives ~E = 2745 N/C at 77.5◦ below the − x axis b) Compute the net force on the 5 nC charge. ~F = q ~E = ( 5 × 10−9 ) ( −600 î− 2697 ĵ ) = −3 × 10−6 î − 1.35 × 10−5 ĵ N/C Or, given magnitude and direction, ~F = ( 5 × 10−6 ) (2745 @ 77.5◦) = 1.37 × 10−5 N/C at 77.5◦ below the − x axis