b. An electric dipole consists of charges of 2.0 x 10°C separated by a distance of 2
mm. It is placed near a long line charge of density 4.0 x 10-4cm- as shown in
the figure below, such that the negative charge is at a distance of 2 cm from the
line charge. Calculate the force acting on dipole.
+
- 2 cm-
2 mm
Line
charge
Answers
Answer:
Explanation:
PHYSICS
An electric dipole consists of charges ±2.0×10
−8
C separated by a distance of 2.0×10
−3
m.It is placed near a long line charge of linear charge density 4.0×10
−4
Cm
−1
as shown in the figure, such that the negative charge is at a distance of 2.0cm from the line charge. The force acting on the dipole will be
question
December 26, 2019avatar
Uttam Himanshu
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ANSWER
The electric field at a distance r from the line charge of linear density λ is given by
E=
2πε
0
r
λ
Hence, the field at the negative charge
E
1
=
0.02
(4.0×10
−4
)(2×9×10
9
)
=3.6×10
8
NC
−1
The force on the negative charge
F
1
=(3.6×10
8
)(2.0×10
−8
)=7.2N towards the line charge
Similary, the field at the positive charge
i.e., at r=0.022m is E
2
=3.3×10
8
NC
−1
The force on the positive charge,
F
2
=(3.3×10
8
)(2.0×10
−8
)=6.6N away from the line charge
hence, the net force on the dipole =7.2N−6.6N=0.6N towards the line charge.