Download Magnetism and Electromagnetic Forces

TIPERs
D3-SCT03: Two M A G N E T S — F O R C E
Three students are discussing the strengths (or magnitudes) of the forces between two permanent magnets. The
smaller magnet is moving to the right. The larger magnet is stronger than the smaller magnet.
v = 0
Alejandro:
"The velocities and magnet strengths don 7 matter. Themagnets will attract each other with equal
strength."
^
Bernardo:
"No, the stronger magnet will push more than the weaker one because it has a stronger field. "
Cecilia:
"/ don't think we can compare the strength of the forces unless we know the velocity of the smaller
magnet."
With which oTthese students do you agree?
Alejandro
r
Bernardo
Explain your reasoning,
ri-
'P'^ Cit/^'/
-f
'"J
Cecilia
/^j^r^^^^^
/^^ Held
None of them
^^y^^^j^j^^
ir^^-^r^
CinameC a^^J
pur
fd
•\/
ffWilC^
J^J
^/
b3-SCT04: ELECTRIC C H A R G E NEAR A B A R M A G N E T — F O R C E DIRECTION
Consider the following students' statements about the magnetic force on a positively charged particle placed at rest
near a permanent magnet.
I
Aurelia:
"A positively charged particle placed near the north pole of a permanent magnet will experience a
repulsive force because the north pole acts like a positive charge. "
Ben:
"/ think it will experience an attractive force, but not because it is a magnet. "
Chila:
"Since it's not moving, I think it won't experience any electromagnetic force."
With which of these students do you agree?
':
Aurelia
Ben
Chila
K
None of them
Explain your reasoning.
Copyright © 2 0 1 5 Pearson Education, Inc.
344
/f^
TIPERs
D 3 - R T 0 7 : M O V I N G C H A R G E P A T H — D I R E C T I O N AND STRENGTH OF T H E MAGNETIC FIELD
In each case, the shaded region contains a uniform magnetic field that may point either into the page or out of the
page. A charged particle moves through .the region along the path indicated. A l l of the charged particles have the
same mass and enter the region with the same initial speed.
B
-
C
)
'
U'-'i lit!''
J
I
u
- +g
1
(
^
1
Rank the magnetic field in the region. Fields directed out of the page (considered positive) are ranked higher
than fields directed into the page (considered negative).
R
1
1
Greatest
/'
2
Explain your reasoning.
'
\
\
3
J
r
iJ^s^-
OR
t
'D
5
4
6
Least
a.
All
All
the same • zero
Cannot
determine
D 3 - R T 0 8 : CHARGED-PARTICLE A N D A UNIFORM MAGNETIC " F I E L D — F O R C E
In each case, a charged particle is moving in a uniform magnetic field. The particle charge and the strength of the
field vary among the four cases. The particles all have the same mass, and they were all given the same imtial speed.
B
? = +9 nC
9 = +5 nC
(? = +15nC
r = 1 cm
r = 2 cm
r = 3 cm
Rank the magnitude of the force on each charge.
,1
Greatest
I
2
II 3 II
OR
4
Least
All
the same
Cannot
determine
All
zero
Explain your reasoning. ^ . ^ ^ ^ . ^ / ^ ^ ^ ^
^ ^ f
^n^^
There
r ^ ^ - i ^
,
/ ^ ^ / ^
~ 2015 Pearson Education, Inc.
346
/
r
t-
TIPERs
D 3 - L M C T 1 0 : M O V I N G C H A R G E WITHIN A UNIFORM M A G N E T I C F I E L D — F O R C E
A positively charged particle moving at a constant speed is entering a region in which there is a uniform magnetic
field. The particle follows the curved path shown.
+1
A number of changes to this imtial situation are described in (a)-(f) below. Select from choices (i)-(vi) how each
change will affect the magnetic force on the particle shortly after it enters the magnetic field.
This change will:
(i)
alter only the direction of the force on the particle.
(ii) only increase the magnitude of the magnetic force on the particle.
(iii) only decrease the magnitude of the magnetic force on the particle.
(iv) alter both the magnitude and direction of the magnetic force on the particle.
(v) not affect the magnetic force on the particle.
(vi) cause the magnetic force on the particle to be zero.
-(f
'
0
^ ' ''
Each change below refers to the initial situation described above:
(a) The +q particle is replaced by a +2q particle.
Explain your reasoning.
r
P*'/
,,
//
r
,
f
(b) The +iy particle is replaced by a » q particle. V qyr a/
- - ^ x p l a i n your reasoning. / / •
^,r,^-
,c
,
/
^
\/
cM'-.;e
J>U. / k^'-fp ^k-e
/o
(c) The +9 particle is replaced by a neutral particle. 1^/
Explain your reasoning. ^ /
^
r-
• t^'J' f ''Of^?Ce
*^<>L?/^^'rr
/^S/^
(d) The particle enters the region moving at a slower initial velocity. • / Explain your reasoning.
^.
-
.
tv^'fi
//.^
(e) The magnetic field is one-third its original strength, f ' /
^Explain your reasoning. / / ' ' . • / , . • - ; , r / y ' y
/
7^/*
(f) The direction of the magnetic field is parallel to the particle's initial velocity.
Explain your reasoning.
1
/
-
,v
/ .
'
.^.n.,...
Copyright © 2 0 1 5 Pearson Education, Inc.
r ......^
^, ......
' k-.^, r::.'.r
i^.^j
</f
,
hit/'
TIPERs
D3-RT13: C U R R E N T - C A R R Y I N G W I R E IN A UNIFORM M A G N E T I C F I E L D — M A G N E T I C FORCE
The figures below show identical current-carrying wire segments in identical uniform magnetic field regions. A l l the
magnetic field regions are the same width and height.
B
D
® (g>i
(g
B
®
®
®
(gi ® (gl
(g (g
Rank the strength (magnitude) of the magnetic force on the wire segments.
1
I
2
II
y/
OR
3
4
Least
Greatest
All
the same
Explain your reasoning.
/
AU
zero
-7~
Cannot
determine
/
X)
D
/•
l/lJ
D3-TT14: P A T H OF A M O V I N G ELECTRON I N A UNIFORM MAGNETIC FIELD
An electron is moving to the right at a velocity v when it enters a region containing a uniform magnetic field
pointing into the paper. The path of the electron in the magnetic field is shown.
\
®
®~® ®~® ®
®l
®'.®I
<8i ® ® %jk % ®|
I® ® ® ® ® ®^^<8i ® ®|
I®
V
10 (g, ^ j g ^ ^ r ®
® ® ® ®i
There is at least one error in the diagram. Identify all errors and explain how to correct them.
{Urvim
C^U/ur/
cToCk'- i^rcr.
/ ' / ^>.o{^,;V
'J
r
Copyright © 2 0 1 5 Pearson Education, inc.
350
'Oi''k:o'/r-y^ fff/'i^C
TIPERs
D 3 - L M C T 1 6 : C U R R E N T IN A UNIFORM MAGNETIC F I E L D — M A G N E T I C FORCE
A section of straight wire within a magnetic field is conducting a current to the right. The external magnetic field is
uniform and directed into the paper.
® ®g
I® ®
® / ® ® ® ®l
; ® ® ® ® ^ ® ® ® ® ® j
L®-®. ®-'^.
^-l^J
A number of changes to the initial force are described m (a)-(e) below. Select from choices (i)-(vii) the possible
causes of the change in the force.
This change could be caused by:
(i)
(ii)
increasing the current.
decreasing (but not to zero) the current.
(iii)
(iv)
reversing the direction of current.
increasing the strength of the magnetic field.
(v)
(vi)
(vii)
decreasing (but not to zero) the strength of the magnetic field.
reversing the direction of the magnetic field.
none of these.
If more than one choice is correct, please indicate all correct choices for the answer.
Each change below refers to the initial situation described above:
(a) The magnetic force on the wire is larger and in the same direction, r . / l.."^
Explain your reasoning.
,^
'
j
r^y)'Jr'A
inUtacf
tarymt
kaj/in^^'^Tvwarie^cC ff£('^ <<xin.
(c) The magnetic force on the wire is smaller and in the same direction.
•
Explain your reasoning.
^ ">
^l^-n^r
^^cfty^r
/LJrr'€rr'
dd'^/'^J'^r
C, / ^ / ( '•/ 9 ' / i
—' '
'
^ /
j
(b) The magnetic force on the wire is larger and in the opposite direction. L ^ (
Explain your reasoning.
^
x
:v^r^'
^.
./
rfefc<
o-r h''^-'.
(d) The magnetic force magnitude remains the same, but the direction changes. / / /
Explain your reasoning.
J
'
.
'
(e) The magnetic force on the wire is zero.
Explain your reasoning.
f I r-'h.y r
C ^'^
^ ^
i
^[ f
,
Copyright © 2 0 1 5 Pearson Education, Inc.
•
, .
r
\/'
ffw^
D 3 MAGNETISM
D 3 - Q R T 1 7 : STRAIGHT C U R R E N T - C A R R Y I N G W I R E — M A G N E T I C FIELD N E A R B Y
The figure below shows a point P near a long current-carrying wire.
f'C (lofy'A ^JM^'j
tjen
i^'^,
"TA^
(a) What is the direction of the magnetic field at point P due to the current in the wire?
I
Explain your reasoning.
oaf
ff'^^ comiAq
j
/
/
-hward
Of •/^-^ f^Ciji^r
utu.
Hfni
tAour
/^^'AT'
-fiiuit?^
(b) WTiat would the direction of the magnetic field at point /" be if the current in the w i r e j w ^ reversed?
Explain your reasoning.
\
//I
fM&uicJ
i
.
cMwmUf tm
^
/
of
df/^Utiyi
/
Hc(^. f-f
*'
/
e^ooufj,
lA-lv -HAE paper -Hr^re,
\
' '
-•
(c) What would happen to the magnetic field at point P if the current in the wire werelncreased?
Explain your reasoning.
/-h
MCcHd
rf^-f
lacl^cry'iJHm
s/rcy^C
S'^'r<^^-^er
f'k
curywi-f-
/y\d^yteHr fe/^^
ci^^
m-ennr
7}t€se
/i^^e
fie/Wr ^Jd
mcuMj
C^P
'
(d) What would happen to the magnetic field at P if point P were farther away from the wire?
Explain your reasoning.
/
.
/
-r?
. ,^ . • ••
iP y-y^
f*^
D 3 - W W T 1 8 : C U R R E N T - C A R R Y I N G W I R E — M A G N E T I C FIELD DIRECTION
A long, straight wire is conducting a current whose direction is pointed out of the paper toward you. A student
makes the following statement:
/
^
"The magnetic field generated by this wire points straight out from the wire."
l/\J
^
What, if anything, is wrong with this statement? If something is wrong, explain the error and how to correct it.
If the statement is valid, explain why.
'/^^ lii.e
Chryi:je rin'^J
pok^
I
hnauu
iUtr€
ycf
J
ekcrric
frffj
IS ri6
ihr^ucfh ^hf'c^
h^mrMj
Copyright © 2 0 1 5 Pearson Education, Inc.
j
^
353
W
U<-f Cf'-aycji
h
-^-^—
f^^
^f'fU
L-urrent-canying wires are positioned at the comers or a square. A l l of the currents have the same magnitude, put
some are into the page and some are out of the page.
B
-^^.-aS
®—fl—0?
1
Rank the magnitude of the net magnetic fidd'atthe center of the square.
OR
1
Greatest
AU
the same
;ast
All
zero
Cannot
determine
Explain your reasoning.
difkkl
Wdwr
^
rtiinf-kml ^^-^^ fir fao- curwnHi^if/ sko^^. ht^f^e
bu,
tifk-rr
"^dd €>/ r^Mc^f
aaik cdk'sy -ut~, A? A-f 0 eaik fi-efj
^/h\/-^-e
^kP^C're
rarn-rr^. I r\
Csmoef, b.^- U-^ h^A-t-r yfr
upper rrfkrP A I R S OF LONGI CURRENT-CARRYING W I R E S — M A G N E T I C FIELD N E A R B Y
^ / , ' ^^^^y,
IS C<ikM(i&d bcjAmfker'
f^pp^ f^fj ^^p^jJ^m^r rtfhf
D3-RT25:
dj/. ^
^ .,
In these cases, the two parallel wires have the same magnimde current perpendicular to the plane of the page. The
direction of the current in each wire is shown.
A
B
c
r
P
e
r
C
c
r
>
r
0
c,
r
P
1r
<
if
>
9
v.r
Rank ti^^agnituj^e of the magnetic field at pomt P.
OR
1
4
Least
Greatest
Explain your reasoning.
\
r
J,.,^frd^
diskrcf
All
the same
All
zero
Cannot
determine
4 ik€
/:&Jcifff
j>r^^'^--^^ ^
Copyright © 2 0 1 5 Pearson Education, Inc.
357
•
u
D 3 MAGNETISM
D 3 - T T 2 7 : MOVING A W A Y POSITIVE C H A R G E NEAR STRAIGHT C U R R E N T - C A R R Y I N G W I R E — F O R C E
At the mstant shown, a positively charged particle has a velocity that is perpendicular to a current-carrying wire.
^^•^
ike
kfrH-f-
(fd^
( b i i w e t n
us
/
fk-e
cck^i
J
&fk/(
A sfaident makes the following statement:
"The force exerted on the charged particle by the magnetic field is zero because the velocity is parallel to the
magnetic field produced by the wire."
There is at least one problem vdth this student's contention. Identify any problems and explain how to correct
fl.^J'Zo...
^
f ^^^^^ d'r^Mj
ry-rkfl,e
^^-^-^
h
D 3 - R T 2 8 : M O V I N G C H A R G E A L O N G A STRAIGHT C U R R E N T - C A R R Y I N G W I R E — A C C E L E R A T I O N
Four charged particles have been projected parallel to identical current-carrying wires. The particles have the same
mass and are projected with the same initial speed.
^ = -1-5 nC
•
•
B
^ = -i-10nC
^
4 cm
+5 nC
4 cm
^ = H-10nC
T
•
2 cm
t
2 cm
Rank th^ magnitude of the acceleration of each charge at the instant shown
p
t
1
Greatest
2
1 A
6
3
4
Least
OR
All
the same
All
zero
Cannot
determine
Explain your reasoning.
kf ^ ^
urn cat
^
'fie(d f^^^^kfh iv
ijk^l
kf^
i ^ / k^Mmck-fnnff^
'kJoatl^
J
J
Copyright © 2015 Pearson Education, Inc.
359
iMm
M^Z
tIPERs
D 3 - Q R T 2 9 : MOVING C H A R G E NEAR A STRAIGHT C U R R E N T - C A R R Y I N G W I R E — A C C E L E R A T I O N
At the instant shown, a particle with charge of +7 nC is moving at 3 m/s parallel to a long, straight wire that has a
current of 8 A.
itm
I
- ,
V = 3 m/s
^
. •>
/
X
/
q = +laC
Ckc'mi
<
/
,c
<
d(€
h
jM
k(d,
/f/S
.
fi^y. WffC
^
- - r r ' C ^ ) ,
(a) What is the direction of acceleration of the charged particle?
Explain your reasoning.
l/yl(t
. /,
/
hcAjcyi^
^
aa.fkrUHnCi
(Ap 'hf.'J^Uci ipy hp ^( -Jk-P ppi>^' ^
c/n it. (mJfy^ h^^^^r poCnfr uJri/n^^o
i^f UrQ.^ix.
forre ackr^
n^tciJk poi>h ink R^M
Mik<
8
fiefd,
pf<
fhukfto
. ^^^'^
(b) If we double the charge on the particle, what will happen to the acceleration?
Explain your reasoning.
/ /
in
^ / / /
pp:u
-o
d^typi^
^
-
fUB^^rk
^^'f^'ir-^j
/" / 5
p
(c) If we replace the charge with la negative charge of the same mass and same magnitude charge as the original
charge, what will happen to the acceleration?
Explain your reasoning.
/ /
^<y/V/
k
^p^O^f^ dir^im ak fkf fdi^€' ra.k.
(d) If we double the distance from the wire to the particle, what will happen to the acceleration?
Explain your reasoning.
/ /
/^//f
fO
/^^
n^(mX€ 1" ^ yfa,
(e) If we double the mass
5s of
of the
the particle,
particle, what
what will
will happen
happen to
to the
the acceleration?
a c c e
l
e
r
d^i'^fr^j
5^
a
t
i
o
n
ri'iru
^
Explain your reasoning.
-'• -
I —
(f) If we double the velocity of the particle, what will happen to the acceleration?
Explain your reasoning.
(g) If we reduce the magnitude of the current, what will happen to the acceleration?
Explain your reasoning,
p .^p,) idpi redco;.: 0i^PaMC£
prop ? ("- y/..
/'•fiduyfrq
iy-^ C^rr
(h) K we reverse the direction of the current, what will happen to the acceleration?
Explain your reasoning,
•jiff
^ ' J ^pppP^J^
£a^'^
ir. PpP^^^^
kP<^k^' ^^rii^'
Copyright © 2 0 1 5 Pearson Education, Inc.
360
d irtci^m-
^iYii