This preview shows pages 1–2. Sign up to view the full content.
Physics 21, Solutions for HW 2:
due online 1 AM, Friday, January 21, 2011
Chapter 22, Problem 4
Two particles are fixed to an
x
axis: particle 1 of charge 6.76 x 10
7
C is at the origin and particle 2
of charge +6.76 x 10
7
C is at
x
= 21.8 cm. Midway between the particles, what is the magnitude of
the net electric field?
Solutions:. With
x
1
= 6.00 cm and
x
2
= 21.00 cm, the point midway between the two charges is located at
x
=
13.5 cm. The values of the charge are
q
1
=
–
q
2
=
–
2.00
10
–
7
C,
and the magnitudes and directions of the individual fields are given by:
9
2
2
7
5
1
1
2
2
01
9
2
2
7
5
2
2
2
2
02

(8.99 10 N m C ) 2.00 10 C
ˆ
ˆ
ˆ
i
i
(3.196 10 N C)i
4
(
)
0.135 m 0.060 m
(8.99 10 N m C )(2.00 10 C)
ˆ
ˆ
ˆ
i
i
(3.196 10 N C)i
4
(
)
0.135 m 0.210 m
q
E
xx
q
E
Thus, the net electric field is
5
net
1
2
ˆ
(6.39 10 N C)i
E
E
E
Chapter 22, Problem 10
Part (a) of Fig. 2233 shows two charged particles fixed in place on an
x
axis with separation
L
. The
ratio
q
1
/
q
2
of their charge magnitudes is 4.05. Part (b) of the figure shows the
x
component
E
net,x
of
their net electric field along the
x
axis just to the right of particle 2. The
x
axis scale is set by
x
s
=
30.3 cm.
(a)
At what value of
x
> 0 is
E
net,x
maximum?
(b)
If particle 2 has charge 5
e
, what is the
value of that maximum? Assume
e
= 1.602 × 10
19
C.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
 Spring '08
 Hickman
 Charge

Click to edit the document details