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12PHYSICS GENERATION SAC
VICTORIAN CERTIFICATE OF EDUCATION
2017
NAME:_________________________
TEACHER: ________________________
PHYSICS
School Assessed Coursework: Test
Generation
Reading Time: 10 minutes
Writing time: 60 minutes
QUESTION AND ANSWER BOOK


Section
Number of
questions
Number of questions
to be answered
Number of marks
A
4
4
41
Students are permitted to bring into the examination room: pens, pencils, highlighters,
erasers, sharpeners, rulers, up to two pages (one A4 sheet) of pre-written notes (typed
or handwritten) and one scientific calculator.
Students are NOT permitted to bring into the examination room: blank sheets of paper
and/or white out liquid/tape.
Materials Supplied
 Question and Answer book of 10 pages. A formula sheet.
Instructions
 Write your student name and teacher name in the space provided above on this
page.
 Unless otherwise indicated, the diagrams in this book are not drawn to scale.
 All written responses must be in English.
At the end of the examination
 Close your Question and Answer booklet and ensure your name and your teacher’s
name is clearly printed on the front cover.
Students are NOT permitted to bring mobile phones and/or any other unauthorised
electronic devices into the examination room.
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12PHYSICS GENERATION SAC
Area of study – Generation
Instructions
Answer all questions in the spaces provided. Use black or blue pen.
Where an answer box has a unit printed in it, give your answer in that unit.
You should take the value of g to be 9.8 m s-2.
Where answer boxes have been provided, write your final answer in the box.
In questions where more than one mark is available, appropriate working should be shown.
Unless otherwise indicated, diagrams are not drawn to scale.
Question 1 (10 marks)
A single rectangular coil of side lengths 5.0 cm and 6.0 cm moves at a constant speed of 1.5 cm s-1. It
moves from Position A outside of the magnetic field, to position B inside of the magnetic field, to
position C again outside of the magnetic field. The magnetic field strength is 0.30 T.
5.0 cm
A
6.0 cm
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B
15 cm
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C
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1.5 cm s-1
a.
Which is the magnitude of the magnetic flux when the coil is in position A?
1 mark
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Wb
b.
Show that magnetic flux in position B is 9 × 10-4 Wb.
2 marks
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12PHYSICS GENERATION SAC
c.
On the axes provided, draw magnetic flux. Take t = 0 s to be the time when the coil first
starts to enter the magnetic field.
2 marks
ΦB (×10 Wb)
-4
d.
Find the magnitude of the induced voltage across the terminals at t = 2 s.
2 marks
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V
e.
What is the induced voltage at t = 8 s. Explain your answer with reference to relevant
physical laws
3 marks
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V
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12PHYSICS GENERATION SAC
Question 2 (15 marks)
The diagram shows a generator with a square coil of side length 8 cm that rotates clockwise at 30 Hz. The
magnetic field in which the coil rotates is 40 mT. The coil has 50 turns.
A
X
a.
Y
What is the magnetic flux through the coil when the coil is in the position shown in the
diagram? Include the unit with your answer.
b. Calculate the magnitude of the average induced EMF between the slip rings as the coil
rotates 90o clockwise from the position shown in the diagram.
1 mark
3 marks
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V
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12PHYSICS GENERATION SAC
c.
In which direction does the induced current flow through the ammeter in the first quarter
turn? Explain your answer.
3 marks
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d. Draw the flux vs. time graph for the two full rotations of the coil from the position in the
diagram. Include a scale on both the horizontal and vertical axis.
3 marks
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12PHYSICS GENERATION SAC
e.
f.
Draw the induced EMF vs. time graph for the two full rotations of the coil from the
position in the diagram. You do not need to include a scale on the induced EMF axis.
3 marks
Describe the changes to the induced EMF vs. time graph above if the coil was replaced
with one that was the same size but had 75 turns and was rotated at 15 Hz.
2 marks
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12PHYSICS GENERATION SAC
Question 3 (11 marks)
Farmer Joe uses running water from a river to turn a turbine that is connected to a generator. The
generator is used to power his electric tools in the shed that is 3 km away and he has run an electrical
cable that has a resistance of 0.003 Ω/m from the generator to the shed and back again. At the generator
he measures a potential difference of 250 V but when he returns to test his power tools, the voltage drop
at the shed is only 150 V and his tools do not run. Farmer Joe knows he requires at least 240 V in order
for the power tools in his shed to run correctly.
V = 150 V
R = 0.003 Ω m-1
V = 250 V
3 km
a.
Show that the current in the transmission lines is equal to 5.6 A.
2 marks
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b. What is the power rating of the generator?
2 marks
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W
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12PHYSICS GENERATION SAC
c.
What power is dissipated during transmission?
2 marks
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W
Farmer Joe decides to use 2 transformers to reduce the power loss during transmission. He uses a 1:20
step-up transformer and a 20:1 step-down transformer.
d. Draw a diagram of Farmer Joe’s situation. Include the generator, transmission cables, the
shed and the two transformers. Clearly indicate which transformer is step-up and stepdown.
2 marks
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12PHYSICS GENERATION SAC
e.
With the transformer arrangement, does Farmer Joe’s shed run the power tools as
expected? Justify with calculations
3 marks
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12PHYSICS GENERATION SAC
Question 4 (5 marks)
The diagram below shows a transformer with 2400 turns in the primary coil and 300 turns in the
secondary coil. The power supply runs at 110 V RMS.
~
a.
V
Find the peak to peak voltage across the voltmeter.
2 marks
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V
b. Explain, with reference to relevant physical laws, how a transformer works
3 marks
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END OF OUTCOME 2