Assignment IB
1. Using symmetry
only need to solve for 1 of the point charges
tnc ,
charges to find the directions of each
we
knowledge of
use our
Jackson F
↳ 2 Kinds of forces
'
:
adjacent & diagonal
•
•
☐
•
↳ adjacent attractive
diagonal repulsive
D
•
Fnetn
.
-_
ppg,
-40008950.63 Ni
←
'
✓
FBC
-
Fa's
"
Fca
Nj)
nF☐a
-
'
)=45SofE=SE
↳ in the middle
⑧ the 2 adjacent forces
→ Fix
÷
using symmetry
>
Fnetn -1.42×10 NSE
Fnet -1.42407N SW
NW
Fnetc= 1.42407N
Fnetis -1.42×10 N NE
-
.
-
.
>
t
10008950.63nF)
I -1.00×10
Knee! -1.4240N
"
Direction:eos"(
Fors
IFn-cxt.tn?a,l--lFn.clsin45-- 5474076.87N
>
Fnetn:-(1.00407N
-
,F•☐
'
(ftp./-/Facd)2+(-/Fn.rsi-lFn.cy)j
-
i.
Fars
-_
IFn.rs/--l5483O27.5N--IFn.Dl
i.
""
/ Fact 7741513.75N
co.it
>
FAD
c•
8.99×10%(4.15×103)
Lr
8.99×10%(4.15×103)
we can
f
>✗
'
"
,
;
ri=Ñ+r°=2r
:
IQ.t-IQ.HQet-IQ.t.IQ/1Fn.d- kfH:lFn.rs- Kr?tf -n.cf=(
/ En #
§
E
:
point A
¥eiK
""
then
N
:
↳
,
2.
Charge
m
is
+ve
because itis
-
-
{ F--0
{F. =D Fe Tx
=
-
EFy=O=Ty
-
cos④
=
the electric field
1:55am -0.55m E- 15000 NIC
-1.0g -0.001kg
-
repelled by
mg
Fe I
:
:
f.
! Sam
-
-
-
-
Ty
-
-
mg
0=38.57270
Ty=TcosQ=mg
FMoscoso
mgsinocoso-mgtanQFe-QE-mgtanOQ-mgtanQ.CO
Fe=Tx=Tsin①=
E
=
i.
001×9.8)tan(38.6)
45000)
5.2×10-7C
The point charge
mass
-
-
-
-
•
-
43cm
55cm
.
-
.
has
a
-7C
charge of +5.2×10
12am
3. oµ=gg= +5 e
""
e--1.602×10
op Be
=
C
=
,
.
m
:
and
q =q
"
D= 5.0mm 5×10
using symmetry
↳ since
94=-12
they
P
are
plane as point P
the net Electric field in the 2C direction
equidistant along
is
the same
+
Y
Be
+
x
zero
↳ op
and
gu
i. we can
are
in line
w/ each other and opposite
compare them to cancel at least
some
of their electric fields
Enet Es É
=
-
"
E. =k¥
.
:
.
:
=
1¥ IE / =k!?¥=%÷=ky¥=kd¥ =/ Ez /
,
Enet =/ Est Est -0
-
-
The net electric field at
point
p is
zero
4. Inner
Layer
f- 0.040m
p
=
9.0 C / m3
Q=pV
① =p ( ¥1TF)
Q :(9.0 Christ¥10.040m}
=
0.002412743 C
=
Outer layer
ro
ri
=
0.10m
=
0.040m
① =pV =p tri Igor?)
ri ri)
=pV=p¥(
-
-
C-3.04ms) 4560.10mi -10.040 mP
=
-0.011762122C
=
Net
①
charge
=
net
=
=
÷
i.
)
f. + ro
(0.0024127-43-0.0117-62122) C
0.009349379
C
-0.0093 C
The net
charge of the
sphere
"
is
-9.3×10 C