Download Excellence

L
90937
NZ
1111111111111 II 1111
~.,,
SUPERVISOR'S liSE ONLY
NEW ZEALAND QUALIFICATIONS AUTHORITY
MANA TOHU MATAURANGA 0 AOTEAROA
2.00 pm Monday 25 November 2013
Credits: Four
'
Check that the National Student Number (NSN) on your admission slip is the same as the number at the
top of this page.
You should attempt ALL the questions in this booklet.
Make sure that you have Resource Sheet L 1-PHYSR.
In your answers use clear numerical working, words and/or diagrams as required.
Numerical answers should be given with an appropriate Sl unit.
If you need more space for any answer, use the page(s) provided at the back of this booklet and clearly
number the question.
Check that this booklet has pages 2-10 in the correct order and that none of these pages is blank.
YOU MUST HAND THIS BOOKLET TO THE SUPERVISOR AT THE END OF THE EXAMINATION.
Low
Excellence
TOTAL
© New Zealand Qualifications Authority, 2013. All rights reserved.
27
ASSESSOR'S liSE ONLY
No part of this publication may be reproduced by any means without the prior permission of the New Zealand Qualifications Authority.
I
2
You are advised to spend 60 minutes answering the questions in this booklet.
ASSESSOR'
USE ONLY
QUESTION ONE: ELECTRIC STOVE TOP
The diagram shows the wiring of an electric stove heating element. The element consists of two
heating coils connected through a switch to a 240 V power supply, as shown in the diagram below.
240V
mains
supply
(a)
heating coil B
The heating coils can be considered as two resistors connected in series with the switch and
the power supply. The switch is in the off position.
In the space below, use appropriate circuit symbols to complete the circuit diagram.
(b)
,------- - -----1Jl 240 V mains supply
Jt-------- - -,
~----~~.~3~,---------11
A
t~------~
The circuit is now switched on.
Explain why the same current flows through both heating coils.
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Physics 90937, 2013
(Y\
3
(c)
Heating coil A has a resistance of 50 n, and heating coil B has a resistance of 40 n.
ASSI:SSOR'S
_'u~r:~~iky
Calculate the amount of power output when the circuit is connected to a 240 V mains supply.
J'·:'_f JL __.JE:._L!fJJ.__~~----'lr£¥.!!::_'1- _V-;:Z(O .
u _6_ :______________
- -----~-s_zzr_
_
--------~--?-~o.-------------::_____1_
o_£]-__ _ _ _ _ _ _ _____
----~-2-~-~'--f:-~-~--~-'2 ffi_____ $ · 1!~1 7 lt_(<z..ilfJ----------------------------------~- ( _4:__
o_.J/Jl_ _ _ _ _ _ _ _ _ _______ _ _______ ~__-z _§.:_~_6.-b__ ~ /1_ ___________________________,___
.e_::____
.
... ..
;
_
__
5-. -.
A second element uses the same heating coils as the one used in the first element, but they are
com1ected as shown in the diagram below.
240'V
mains
supply
--~-:
heating coil B
~:--. ~:
,-~
(d)
The element is switched on. In the space below, use appropriate circuit symbols to complete
the circuit diagram.
I
240 V mains supply
I
. :·..
---··-~-
J
I
[5
-·
A
(e)
I,J
·;-·
State and explain how the power output of the above element differs from that in the :first
element in Question One (a), when both elements are connected to a 240 V mains supply.
.":·•-
·:--
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:;::~6
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...
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4
QUESTION TWO: MAGNETIC EFFECTS
(a)
(i)
USE:OI'IJ..l
Describe what is meant by the tenn magnetic field .
A"' rru-L"' . \ !l vAnL, . Ovrcv(ii)
ASSESS OF
0 a&-f-d..
Ify.Pt
fl1qfllfi
·~ it_~{tj~ J!:J::1 &C::fl~~;~yz;J !f}tJlJJ&
Two compasses are placed near a bar magnet, as shown in tVe diagram below.
Draw an arrow inside each circle to show the direction in which the compass needle will
point.
Physics 90937 , 2013
()\
r.
I!
5
The diagram below shows the arrangement of a magnetic catch on the wooden door of a kitchen
cupboard. It consists of a magnet set in the wooden door and a piece of soft iron set in the wooden
frame.
·:-
I
(c)
soft iron in
wooden frame
magnet in
wooden door
Use the idea of induced magnetic poles to explain what takes place as the magnet in the door
approaches the soft iron in the frame, and why the door is firmly held against the frame when
it is shut.
You may draw on the diagram to aid your explanation.
lls _kk_~at8_Ji~'i -- u~c~t{ltbt:L~lj'
Jik_W~t~'lf!!{f~~~~~-~Ili-.w_f~~&t~- -- u ---~~~~~~ ~ .lLV--f-L-&LL-_rn0Ln;AJ1 __ 16-_t __
~-"<;1-+'h --BtdL ~~i.L ~La.
____
~IVldLfi,~~~fk_- ~~.vu~~;~;lp~ft ·. CL .
Jz_&-~~L_______f£wLLb-c:..q;-L<tfL_. ~-
if f "L&'VI"Jrfl-7 li~ Jof2/- ~/
(d)
.
sw_ __~ftffl
N
{ltuf~)1
You are given a magnet and a metal bar. The metal bar is either a soft iron or a magnet.
Physics 90937, 2013
r> ,
F1
I' I
6
QUESTION THREE: MORE MAGNETIC EFFECTS
AS§E_SS(
-- US!;! ON
The diagram below shows the features of a magnetic separator used in a recycling station to
extract iron from a mixture on a conveyor belt. It consists of an electromagnet with a soft iron core
connected to a power supply. The arm swings above the conveyor belt and the switch is closed.
The arm then swings over to a container and the switch is opened to release the material into the
container.
. _,
swinging
arm
.;
'. i
power
supply
'>
variable
resistor
(a)
On the diagram below, use the letters 'N' and 'S' to label the north and the south poles of the
electromagnet.
(b)
On the same diagram, draw the shape and the direction of the magnetic field inside the iron
core.
...._
:
i
:I
:1!
' I
l
(
i
Physics 90937, 2013
...
7
The cables inside the swinging arm connect the electromagnet to the power supply. When the
cunent passes through the cable, a magnetic field is set up around it.
ASSESSOR'S
USE;Q~LY
The value of k is 2.0 x I0-7 T m A- 1•
swinging
ann
'
15
em :'
'
•x
(c)
The power supply is set at 150 V, and the total resistance of the circuit is 25 Q , including the
variable resistor.
Calculate the strength ofthe magnetic field due to the lower cable at a point 15 em away from
r ,
it.
·
VI
--~--~ - ~-------------~ _:__~~-6.KlO___?fmA.~i _ _ _I_~_
_zg_________~?::JSQ. _&?_?J
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_________________ . . ·--- ..
?
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T
[_dfJ__:_~_~_[_ _ _ --------
(i)
-~
~--:~;,_.:_
.
.. : ;:; .
__ ;
··~
Strength ____
J!
(d)
:
.
Explain why the variable resistor is included in the circuit.
~~__y fJL_c~K~2Dftu::__LL_du_d_k_slo-i! _gL
_cdcW~t _(l~fr'l.-~ j- JJUeckx~.yd__ 1AL(f4_/k
_2 fN~_LLL {Q:U ~- 0JL/k___df~~-fl,.._fL-~
--~------~~~E__k __c{~--f.2--. Ji~-----~<3ftd~L{~----- ---·
(ii)
Explain why the device would still work if the polarity of the power supply is reversed.
_tL4t-fM1CJ.r}r-JL- ~l!:Jdk~ _&___dfdD.'U~td..(L -I&if
_\t&_v:i_FW'tuLt_k:kL~ u-s~-----K-~____M ye.f[i_&rlrl
- ~cA_
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·.-.
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0
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8
QUESTION FOUR: CHARGE INTERACTIONS
(a)
ASSESS(
USE Oil
When hair is combed with a plastic comb, the comb becomes negatively charged.
State the type of charge on the hair, and explain why hair becomes charged this way.
Jk1,._k.L"-s . bu~J< . p.Q_JCt<~it ·-&~d_PJ.t:gf.eef&.J
hs.iie: . h_L.£.(\ ... '? frLf{ktA_{rrJtlt . ri:~ ...C!JCJ£l.pf&d(!ll ...
Ke.-.. .L ~ t1 9Nlhj . }he .fv.~1.'r . <1 .ddhll: all d~
(b)
oTJlff!:{:l?~?i;~J!/ii!J!!r~~~t~a?1~
The dtagram sliows a chlrged stnp of sticky tape hung uom a wooden shelf There are ''"'
two charged rods on the wooden shelf. Rod A is positively charged, and rod B is negatively
charged.
•... ··rrl:e~r
charged
sticky tape
Physics 90937, 2013
I
u
r.
9
(c)
Some apple growers use electrostatic spraying of chemicals to protect plants from insects. In
the diagram, the apple tree in the soil is earthed. The spray gun is connected to a high voltage
positive supply.
,:
-;
'
-~
.~
,i\I
''
For copyright reasons, this image cannot be reproduced here.
http://biology.phillipmartin.info/biology_apple_tree.html
ASl!ESSOR'S
', U~~qijLY
·_ -.. ~~~
::.-
L
90937
_, NZ
1111111111111111111
SUPERVISOR'S USE ONLY
NEW ZEALAND QUALIFICATIONS AUTHORITY
MANA TOHU MATAURANGA 0 AOTEAROA
2.00 pm Monday 25 November 2013
Credits: Four
'
Check that the National Student Number (NSN) on your admission slip is the same as the number at the
top of this page.
You should attempt ALL the questions in this booklet.
Make sure that you have Resource Sheet L 1-PHYSR.
In your answers use clear numerical working, words and/or diagrams as required.
Numerical answers should be given with an appropriate Sl unit.
If you need more space for any answer, use the page(s) provided at the back of this booklet and clearly
number the question.
Check that this booklet has pages 2-10 in the correct order and that none of these pages is blank.
YOU MUST HAND THIS BOOKLET TO THE SUPERVISOR AT THE END OF THE EXAMINATION.
Excellence
TOTAL
© New Zealand Qualifications Authority, 2013. All rights reserved.
ASSESSOR'S USE ONLY
No part of this publication may be reproduced by any means without the prior permission of the New Zealand Qualifications Authority.
2
You are advised to spend 60 minutes answering the questions in this booklet.
--:·-5
Jl.SSESSOI'i'l
.- USEON~Y
'·
QUESTION ONE: ELECTRIC STOVE TOP
.~-
The diagram shows the wiring of an electric stove heating element. The element consists of two
heating coils connected through a switch to a 240 V power supply, as shown in the diagram below.
.·~..:.·
240V
mains
supply
(a)
heating coil B
The heating coils can be considered as two resistors connected in series with the switch and
the power sppply. The switch is in the off position.
;
~-.
In the space below, use appropriate circuit symbols to complete the circuit diagram.
240 V mains supply r - - - -- ---,
--·
(b)
.;
,..
',
.....
The circuit is now switched on.
_,,_' ·,
Explain why the same current flows through both heating coils.
~fi~ ___ c\fi:D\tr ~ CUff\ef\t .li__-.!iley___h_.fttMe
~ro~ out- k
0Vuv il.,__.:Iha_J be.cqus~ 1~ 'J/IZ 1 gAd
__ 1.t\ q
OC CU.jJS~ ~lLJ2{ htJe-_iL_'fN
'$
CtO.kt~
~WI
edt
~ 11M~
~ f\e-t5 t;s+ot.sj
0
t'rt.
fu
fo/-q I__ri~ ~d"Ctt? {e___
Lurrent 1s eq,v v. l 1hf'o VJ ~t.9V t-i f
fJ..fi.
Physics 90937, 2013
--
-.-
_.,
3
(c)
Heating coil A has a resistance of 50 .Q, and heating coil B has a resistance of 40 n.
Calculate the amount of power output when the circuit is connected to a 240 V inains supply.
2.%
'Yt;
___ Y.__~_I_g_________ T_~ ____g_______________ 1 ::_____________ _5__6
---------------~---------------------------------
_ £.:_r _::L_________E :::
-
"2-40
-L4_Q ____:_____~---------- __ ----------------------------------
r : . __2 .~~~~~~A____________________
;~~ ~ b b ~- 21f:Q________
__________________________________
p :: b40
\1\)
~ ~:
~·---
•.: ..
A second element uses the same heating coils as the one used in the first element, but they are
connected as shown in the diagram below.
2401./
mains
supply
(d)
. heating coil B
The element is switched on. In the space below, use appropriate circuit symbols to complete
the circuit diagram .
.-------,---------1:
240 V mains supply
:1--- -------,
_.·.·
L
(e)
State and explain how the power output ofthe above element differs from that in the first
element in Question One (a), when both elements are connected to a 240 V mains supply.
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6
__ .512____~ --~L~t.eDA: ____~_l:f_~___ i_fl E~~~--------------------- -------- --------- _____________________________
Physics 90937, 2013
M
..·..
-·~
4
QUESTION TWO: MAGNETIC EFFECTS
(a)
(i)
ASSESSOR'
USE ONLY
Describe what is meant by the term magnetic field .
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__d~~-io__lN:__~_U____~!Vt a ~--"-eltied --P 6J-t:cl_, --&~.r~J:~fi_dd.£__q_l~yJ
\N'ove~ ovf- o-t--- ~ lf\Or.f}.:
(ii)
tine.\ 11"\--:> -fi~ So·ufh '(CO/-e ,r//
Two compasses are placed near a bar magnet, as shown in the diagram beloW:
-po'.e
Draw an arrow inside each circle to show the direction in which the compass needle will
point.
e
.
(b)
.
.
Explain why a magnet attracts an iron nail but not a pencil lead.
_;;(Qfl.l';[___q__~
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.
f
..
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flbl\ al\~f\~ ~1"\s~\ves l s-o ~.r ~piece of-- froY\
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v ~v-tf-vre
ti-1-\-ya c/--ut
1-v 1'Lt
b-e c 6M-tj
VV\'<ytt+-p-
,...
......··
..' ~
Physics 90937, 2013
5
The diagram below shows the arrangement of a magnetic catch on the wooden door of a kitchen
cupboard. It consists of a magnet set in the wooden door and a piece of soft iron set in the wooden
frame.
ASSES-SOR'S
· u:~e6NLY
~~~ .-.::.•
magnet in
wooden door
soft iron in
wooden frame
(c)
Use the idea of induced magnetic poles to explain what takes place as the magnet in the door
approaches the soft iron in the frame, and why the door is finnly held against the frame when
it is shut.
You may draw on the diagram to aid your explanation.
__
pole
m~ ~~ViS I0 Ol..QJ. fk l _co r:_g_!i n___~_~_g_e~__:fi_ _f~_lhcd=___fu_f_q_~,---~.Q p ::. ;_ -
3
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~-~___:furc~___of___!kt~e_fil_~~------------- ---------- ------------------------------------------- _
(d)
You are given a magnet and a metal bar. The metal bar is either a soft iron or a magnet.
Explain how you could find out if the metal bar is a magnet or not.
Vsl~__k
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Physics 90937, 2013
_,
6
QUESTION THREE: MORE MAGNETIC EFFECTS
ASSESSOR
USE Olfl.~
The diagram below shows the features of a magnetic separator used in a recycling station to
extract iron from a mixture on a conveyor belt. It consists of an electromagnet with a soft iron core
connected to a power supply. The arm swings above the conveyor belt and the switch is closed.
The arm then swings over to a container and the switch is opened to release the material into the
container.
soft iron
swingmg
arm
power
supply
conveyor belt
(a)
variable
resistor
On the diagram below, use the letters 'N' and'S' to label the north and the south poles of the
electromagnet.
0..
(b)
On the same diagram, draw the shape and the direction ofthe magnetic field inside the iron
core.
Physics 90937, 2013
7
The cables inside the swinging arm connect the electromagnet to the power supply. When the
current passes through the cable, a magnetic field is set up around it.
ASSES.SOR'S
USE,ONLY .
The value ofk is 2.0 x I0-7 T m A- I_
swmgmg
ann
'
15
em :
'
•x
(c)
The power supply is set at 150 V, and the total resistance of the circuit is 25 0 , including the
variable resistor.
.-~
Calculate the strength of the magnetic field due to the lower cable at a point 15 em away from
it.
=- 1 R
v
1~0~
'5:::-.
1:::
Y121
">
/(_s_. _________________
r~6 L:l
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(l
'
-~
-r
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-a-; Q.OOODO{£ \
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-b
Strength ·----~--~---~Q____________.l~J.i::e._______
(d)
(i)
Explain why the variable resistor is included in the circuit.
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.. g _
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Explain why the device would still work if the polarity ofthe power supply is reversed .
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QUESTION FOUR: CHARGE INTERACTIONS
(a)
When hair is combed with a plastic comb, the comb becomes negatively charged.
State the type of charge on the hair, and explain why hair becomes charged this way.
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(b)
The diagram shows a charged strip of sticky tape hung from a wooden shelf. There are
two charged rods on the wooden shelf. Rod A is positively charged, and rod B is negatively
charged. ;
wooden
shelf
charged
sticky tape
Explain how you could find out the type of charge on the tape using the rods.
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(c)
Some apple growers use electrostatic spraying of chemicals to protect plants from insects. In
the diagram, the apple tree in the soil is earthed. The spray gun is connected to a high voltage
positive supply.
ASSESSOR'S
l,ISE ONLY
positively charged
spray gun
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Explain why both sides of the leaves receive spray when electrostatic spraying is used.
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dryer, the clothes stick together.
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Using the idea of static electricity, explain why the dry clothes stick to each other after being
removed from the dryer.
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The score range for Excellence runs from 27- 32. These two Exemplars scored 27 and 29, as
noted on the covers.
Low Excellence
l(e) Good link between higher current, same voltage and higher power supported with appropriate
calculation.
2 (a) To gain merit the student needs to show the correct direction of the magnetic field- top arrow
should be horizontally to the left
2 (b) To gain merit the answer needs to link the magnetisation of iron to the presence of an external
field (reference to attracting electrons is incorrect)
2 (d) To gain merit in this question the student would need to recognise that soft iron would be
attracted to the magnet.
3 (d)(i) to gain excellence this part needs to link the strength of the electromagnet to the size of the
electric current flowing.
4 (d) This answer correctly explains charge on clothes due to excess of positive/ negative charges. It
also explains why charge is retained on clothes as clothes are insulators.