Download Potential Practice Test Answers

AI' Advanced
Physics Potential
practicc test
Name:
y
Q
+
d~
+q
A
,
,
•..o ----d
;0
---
B
2d
...£
as shown above.
I. At which of the following points is the electric field
least in magnitude?
A
Q
I
I
Questions I -2 Two positive charges of magnitude q are
each a distance d from the origin A of a coordinate systcm,
trY
•
C
Jd
(B) B
(C) C
x
Positive charge Q is uniformly distributed over a thin ring
of radius a that lies in a plane perpcndicular to the x-axis
with its center at the origin 0, as shown above.
5. The potential V at points on the x-axis is represented by
which of the following functions?
(0) 0
(E) E
o At which of the following points is the electric potential
(C) V(x) = k~
x-
(D) V(x) = kQ
x
greatest in magnitude?
(B) £3
(C) C
(0) 0
Ouestions 3-4 refer to a sphere of radius R that has
positive charge Q uniformly distributed on its surface
3. Which of the following represcnts the magnitude of the
electric field E and the potential V as functions of r,
the distance from the center of the sphere, when r < R
?
.E
V
0JO
kQ/R
(£3) 0
kQ/r
(C) 0
0
(D) kQ/r'
0
(E) kQ/R'
0
4. Which of the following represents the magnitude, of the
electric field E and the potential V as functions of r,
the distance from the center of sphere, when r> R ?
.E
V
(A) kQ/R'
kQ/R
(£3) kQ/R
kQ/R
(C) kQ/R
kQ/r
~kQ/r'
kQ/r
(E) kQh)
kQ/r'
(E) V(x)
=}5L
a+x
6. Which of the following graphs best rcpresents the
electric field along the positivc x-axis?
(Al
:~=--,re :h---,
AP Advanced
Physics Potential
practice test
Name:
------------------
10. A positive electric chargc is movcd at a constant speed
between two locations in an electric field. with no
work done by or against the field at any time during
the motion. This situation can OCClll" only if the
(A) charge is moved in the direction of the field
7. Concentric conducting spheres of radii a and 2a bear
equal bnt opposite charges +Q and -Q. respectively.
Which of the following graphs best represents the
electric potential V as a function ofr?
(Al~
(8)~
(8) charge is moved opposite to the direction of the
field
(C) charge is moved perpendicular to an equipotential
line
@charge
o
20
Q
(0'r ~ i
roo
20
'
@L
o~r
0
a
20
is moved along an equipotential line
(E) electric field is uniform
II. A positive charge 01'3.0 x 10" coulomb is placed in an
upward directed uniform electric field of 4.0 x 10'N/c.
When the charge is moved 0.5 melcr upward, the work
done by the electric force on thc charge is
'
~
6 x 10'" J
(0)8xI0'J
8. What is the radial component of the electric field
associated with the potential V = at" where a is a
~
B) -2a('
C) a('
0) 2ar"
v
F.
.,
o
c
9.
The graph above shows the electric potential V in a
region of space as a function of position along the
x-axis. At which point would a charged particle
experience the force of greatest magnitude?
(A) A
(E) E:
(B) B
(C) C
X
10' J
12. A potential difference V is maintained between two
large, parallel conducting plates. An electron starts
from rest on the surface of onc plate and accelerates
toward the other. Its speed as it rcaches the second
plate is proportional to
(A) ltv
(E) V'
2ar-]
(C) 2
(E)12xI0'J
constant?
A) -2a('
(B) 12 x 10'" J
(B)
l/JV
(0) V
AP Advanced Physics Potentia! practice test
Name: -------
I. A solid metal sphere of radius a is charged to a potential V > 0 and then isolated from the
charging source. It is then surrounded by joining two uncharged metal hemispherical shells of
0
inner radius b and outer radius 2b. as shown above, without touching the inner sphere or any
source of charge.
a.
Inlerms of the given quantities and fundamental constants, determine the initial charge 00
r~O.
on the solid sphere before it was surrounded by the outer shell.
I
-~,..
V-=-
j<-
1'-
Q
Ct
Q. -=
b.
(J,Vo
Indicate the induced fharge on the following after the outer shell is in place.
i. The inner surface of the shell
b
-(10
10
ii. The outer surface of the shell
+Q
I:, -::;'lC-Q
c)
c.
~
Indicate the magnitude of the electric field as a function ofr and the direction (if any) of the field for the regions indicated
below. Write your answers on the appropriate lines.
Lr<a
D
Magnitude
Direction
0... V.
~
r
ii. a < r < b Magnitude
o
iii. b< r< 2b Magnitude
Direction
Does the inner sphere exert a force on the uncharged hemispheres while the shell is being assembled? Why or why not?
'1~
e.
Direction
Magnitude
iV.2b<r
d.
Direction
r
I
invv..-r
-t Q
i\"\.c\~
-~
()}'\.inn.u-
4;Q
~~
~~
~
U
~
~
~
~
~:
\<.~ -::;o..~o
v(r~Vo)=
r -
J
-
0
~
\.
_ VCr) _ V(f'-I!:'o' _ ~
- ~
-=
'r
r
'2-'0
(-=.o.. v- 0...V [.l. __I
V [\
"
I}...
hN-(>eS
c4«
Oh. ih hU' IS fitr(
Ahhough the charge on the in,!.!r solid sphere has not changed, its potential has. In terms orv.,
potential on the inner sphere. Be sure to show your work.
~o..Q
~c~s.
J-
'2.'0
-
0
\~~
L
l~)
'i:l(>~
'!<-J 0.. Vo \ _
t'\
-
'r')
'" 'I -y,
2.bJ
-
0.
v.
'2....,
a, and b, determine the new
~;:t~
~J
~ 0-. VO
~
II"W"R-rS;'T'-
U:- - ii,,)
AI' Advanced
Nmne:
Physics Potentia! practice test
+30 V
+20 V
_
+10 V
-10 V
-20 V
-30 V
-40 V
2. Three point charges produce the electric equipotential lines shown on the diagram above.
a. Draw arrows at points L, N. and U on the diagram to indicate the direction of the electric tield at these points.
b.
At which of the lettered points is the electric field E greatest in magnitude? Explain your reasoning.
T
c.
etiAi p6\:r~o,...Q
e,A..o'>.<-* 1-0~
-=-('500
-= !£-.02
J
Y...
1"\
Compute all approximate value for the potential dilference, v" - V,. between points M and S.
v"" - V S
e.
~
Compute all approximate value for the magnitude of the electric field Eat poillt P.
t ::~
b);
d.
~
=
yo - '5
=
1>'5 V
Determine the work done by the field if a charge of +5 x 10.12 coulomb is moved from point M to point R.
W=qbV
::('3)<\0'17.)( ~O 11
w - '51.IDf.
~{)J
0
If the charge 01'.+5 x 10.12 coulomb were moved from point M first to point S, and then to point R, would the answer
to (e) be different, and if so, how?