3 cov lus nug txog cov qauv hluav taws xob
1. Ib lub pob uas siv hluav taws xob nrog lub vojvoog ntawm 10 cm muaj lub zog hluav taws xob ntawm 500 μC. Cov ntsiab lus A, B, thiab C pw hauv kab nrog lub hauv paus ntawm lub pob ntawm qhov deb ntawm 12 cm, 10 cm thiab 8 cm ntawm lub hauv paus ntawm lub pob. Xam lub zog hluav taws xob ntawm cov ntsiab lus A, B, thiab C!
Paub Tias:
Lub vojvoog ntawm lub pob hluav taws xob (R) = 10 cm = 0.1 m
Lub zog hluav taws xob (q) = 500 μC = 500 x 10 -6 C
r A = 12 cm = 0,12 m
r B = 10 cm = 0,1 m
r C = 8 cm = 0,08 m
Coulomb tas li (k) = 9 x 10 9
Xav tau: Lub zog hluav taws xob ntawm qhov chaw A (E A ), ntawm qhov chaw B (E B ) thiab ntawm qhov chaw C (E C )
tshuaj:
a) Lub zog hluav taws xob ntawm qhov chaw A
E A = kq / r A 2 = (9 x 10 9 )(500 x 10 -6 ) / (0,12) 2 = (4500 x 10 3 ) / 0,0144 = 312500 x 10 3 = 3,125 x 10 8 N/C
b) Lub zog hluav taws xob ntawm qhov chaw B
E B = kq / r B 2 = (9 x 10 9 )(500 x 10 -6 ) / (0,1) 2 = (4500 x 10 3 ) / 0,01 = 450.000 x 10 3 = 4,5 x 10 8 N/C
c) Lub zog hluav taws xob ntawm qhov chaw C
E C = 0 rau qhov nyob hauv lub pob.
2. Yog tias muaj qhov ntsuas hluav taws xob 4 nC nyob rau ntawm ib qho chaw, qhov ntsuas hluav taws xob ntawd yuav muaj zog li 5 × 10 – 4 N. Qhov loj ntawm lub teb hluav taws xob E ntawm qhov chaw ntawd yog dab tsi?
Paub:
Ntsuas hluav taws xob (q) = 4 nC = 4 x 10 -9 Coulomb
Lub zog hluav taws xob (F) = 5 × 10 -4 N
Xav tau: Qhov loj ntawm lub zog hluav taws xob (E)
tshuaj:
E = F / q = (5 × 10 -4 ) / (4 x 10 -9 ) = 1,25 x 10 5 N/C
3. Ob lub nqi q B = 12 μC thiab q C = 9 μC raug muab tso rau ntawm cov ces kaum ntawm daim duab peb sab zoo li hauv daim duab. Txheeb xyuas lub zog hluav taws xob ntawm qhov chaw A!
Paub:
Them ntawm qhov chaw B (qB) = 12 μC = 12 x 10 -6 C
Them ntawm qhov C (qC) = 9 μC = 9 x 10 -6 C
Coulomb tas li (k) = 9 x 10 9
r AC = 4 cm = 0,04 m
r AB = 3 cm = 0,03 m
SE pob: lub zog hluav taws xob ntawm qhov chaw A
tshuaj:
E AC = kq / r2 = (9 x 10 9 )(9 x 10 -6 ) / (0,04) 2 = 81 x 10 3 / 0,0016 = 5,0 x 10 7 N/C
E AB = kq / r 2 = (9 x 10 9 )(9 x 10 -6 ) / (0,03) 2 = 81 x 10 3 / 0,0009 = 9,0 x 10 7 N/C
