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Two charges of -4 and +4 are placed at the points A(1, 0, 4) m and B(2, -1, 5) m located in an electric field E=0.20 i V/cm. The magnitude of the torque acting on the dipole is 8 10-5 Nm, where = .
2
Dipole moment points from -q (A) to +q (B): p=q AB
AB=(2-1) i+(-1-0) j+(5-4) k= i- j+ k
p=4 10-6( i- j+ k) C m, E=0.20 V/cm=20 i V/m
= p E=80 10-6( i- j+ k) i
=8 10-5( j+ k)
| |=8 2 10-5 N m =2
Answer: 2
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